Tires and wheels – Page 8 – RoadTraveler.net

October 30, 2017September 6, 2018

Tread Matters: Tire Selection and Fuel Economy

Tread Matters: Tire Selection and Fuel Economy

Tires have been a popular subject in magazines for decades, and forums continually see new threads seeking information and expertise. This is partly because they are expensive. They can also provide dramatic style and performance improvements and are an easy upgrade. With so much talk, it is surprisingly difficult to get unbiased, detailed, and authoritative information.

Fuel economy is another perpetually popular topic. Since tire choice affects mpg, or so we have always believed, the subjects are intrinsically linked. Some folks don’t care about mpg, but many care a lot. Except for the purchase of a new(er) truck or major repairs, fuel is our biggest operational expense.

What if it was possible to improve your highway mpg by 5 or 10%? Not a possible increase from the latest magic program pushed by a snake-oil salesman, but simply by choosing a different tread design? An improvement that could be measured and verified, repeatedly, with real world testing, not just theory or laboratory results that are difficult, if not impossible, to replicate.

What Affects MPG?

In the enthusiast truck world it is commonly accepted that bigger rubber reduces miles-per-gallon. Maybe, but bigger is not specific, sometimes it means wider, taller, or both. Taller tires will increase the overall final-drive-ratio, which can help or hurt efficiency depending on the platform and usage.

Previous tests with my 3.42:1-geared, 2014 Ram/Cummins 2500 used for this article indicate that taller meats up to 35” helped economy, or at least hurt mpg less than one might expect when unloaded. Tradeoffs include less torque and slower acceleration from higher final-gearing, though current generation trucks make plenty of torque and horsepower for most reasonable loads. My sense is that stepping-up to 37s would require lower differential gears for optimal performance.

When folks upgrade their tires, particularly on a four-wheel-drive, they often switch to a higher-void pattern; sometimes the more aggressive tread is chosen simply for looks. Even if we don’t mind the road noise or faster wear of an aggressive pattern, how much fuel does looking cool consume if one rarely or never drives off-road? With multiple, simultaneous changes, it’s impossible to say what caused a reduction in fuel economy. Instead of belaboring what modifications can do to our trucks, or what affects what, I’ll briefly quote myself, “Modifications lead to modifications.”

Beefier tires might cost you more mpg than you think.

Three great tread choices depending on your priorities.

Controlling Variables With Cooper Discoverer Tires

With generous support from Cooper Tires, I performed a series of real-world tests to document how tread design (or pattern) or tread width impacts fuel economy. I invested a substantial amount of time and money to prove or disprove commonly accepted hearsay and to produce solid data I could not find anywhere. The pattern design tests are complete, and my procedures are detailed below together with the results in Table Two. The width results are concerning, or at least surprising, and additional work may be necessary to become comfortable with the facts.

The primary variable to be controlled for the design test was the size, but weights, odometer and speedometer error, wind, and temperatures were also logged. The bullet list below offers details.

Weather forecasts were monitored until several similar days were on the horizon. Because wind is common in Nevada, and typically increases with the afternoon temperatures, just one test was performed each morning, avoiding the higher winds and heat that would influence outcomes if I conducted multiple runs each day.
Three used sets of the same 29.8-pound, forged-aluminum (WBJ) Ram Bighorn 18” wheels were purchased from Craigslist, allowing all tires to remain mounted and balanced in case a test needed repeating.
Odometer error was measured for every design using mile-markers (MM) and GPS, as different treads in a certain size are not dimensionally identical. A single, constant-GPS distance was used for all mpg calculations. Road speed was monitored with GPS and corrected speedometer measurements.
To reduce the possibly of substantial inaccuracies during fueling, and to increase the validity of the data, the roundtrip route distance was 222.7-miles, over mostly level freeway.
Refueling was done at a particular pump, on the slowest fill rate to prevent foaming, and never topped-off. The freeway onramp is just one mile and three stoplights from the filling station.
Appropriate, not maximum, pressures were used for the modified but unloaded truck- 8,900-pound GVW.
The tailgate was up and the A/C was on.
Cruise control was used and only adjusted or turned-off briefly when absolutely necessary, and notes were logged regarding any irregularities. If an accident, construction, or other mishap would have caused stopping or a substantial speed adjustment for an extended distance, I would have aborted and repeated the test.

EVIC mpg info is often inaccurate, doing the math is better.

All-Terrain, Commercial Traction, Or Mud-Terrain?

When enthusiasts upgrade their rubber it’s common for choices to fit into one of three categories; all-terrain, commercial traction (hybrid), or mud-terrain. I chose the LT295/70R18E size, which is approximately 34” tall and 12” wide, with an impressive 4,080 pound capacity at 80 psi. Cooper offers three of their popular, yet distinctly different Discoverer patterns in this size: the Discoverer A/T3, Discoverer S/T MAXX, and Discoverer STT PRO.

Readers should remember than although every effort was made to limit variables, these were real-world tests using off-the-shelf products; some differences naturally exist. One easily overlooked fact is that tire compounds are proprietary, and each has its own special cocktail. Tread depth, and sidewall and tread plies also vary depending on the terrain and audience targeted. So the differences affecting performance and mpg are not just the visible patterns, but they include the compounds and the overall construction of each tire.

Cooper A/T3, S/T MAXX, and STT PRO designs.

Discoverer 295/70R18E Measurements

The differences between tires of a particular size are often small, though one should be careful when comparing those from different manufacturers and/or a vastly different pattern. Over the past decade I’ve evaluated several sets of Cooper-branded and Cooper-manufactured tires, and my measured values have repeatedly matched the published specifications. Occasional, slight variations appear to be from measuring tools, mounting on narrower rims, etc. Manufactures know precisely what they are producing; they want to be as accurate as possible. Careful measurements were made of each Cooper design, and the details are in Table One.

Reading forums leads me to believe that some consumers don’t measure accurately, and/or expect the on-vehicle dimensions to be identical as the wheel-mounted, off-vehicle measurements; these folks cry foul when they are not. That is silly, as the weight of the vehicle, psi, and wheel width all affect the on-vehicle stature, and this is something the manufactures have no control over.

If you read carefully, and do some math, you may notice that the measured weight of a solo tire, plus the 29.8-pound wheel, does not match the mounted data, there are a few extra pounds in the sums. I’ve seen this many times before, as measuring bare wheels is difficult, and generally I must hold them against my chest and subtract my body weight. The figures listed in table one are what my shop scale, a good bathroom scale, indicated, plenty accurate for weighing heavy auto parts. Emphasis should be placed on the mounted weights, as nobody drives on wheels without tires. The few pound difference between these designs is negligible on a heavy-duty truck with prodigious torque and weighing nearly 9,000 pounds.

All 295/70R18 tread designs were about 34.25” tall.

Straight edge, a rule, and a keen eye were used to record height and width.

Table One, 295/70R18 Measurements

Cooper Discoverer 295/70R18	A/T 3	S/T MAXX	STT PRO
Weight (pounds)	60.2	66.4	68.8
Weight mounted (pounds)	92.0	97.4	99.8
Height unmounted	33 11/16”	33 13/16”	34”
Height mounted @60	34 4/16”	34 5/16”	34 5/16”
Tread width	9 7/16”	9 10/16”	10 3/16”
Tread depth	17/32”	18.5/32”	21/32”

Table Two, Tread Affecting MPG Test Data

Tread Matters MPG 295/70R18	A/T3	S/T MAXX	STT PRO
Test GVW (pounds)	8,900	8,900	8,900
Tire PSI F/R	60/40	60/40	60/40
Date	9-28-16	9-27-16	9-29-16
Time	0832–1202	0859–1230	0837–1208
Temperatures F	54-59-72-70-76-72	52-58-67-73-75-78	58-60-56-69-79-76
Wind/Gusts	1/2-5/5-2/5-4/4-1/2	4/4-2/3-0/0-1/2-0/0	0/0-3/4-5/6-3/8-0/0
Odometer	27,241–27,459	26,950–27,168	27,503–27,721
Trip Odometer	217.6	217.7	217.5
Odo error % MM & GPS	2.24/2.34	2.17/2.29	2.28/2.39
GPS (miles)	222.7	222.7	222.7
MPH indicated	64	64	64
MPH GPS	65.0–65.5	65.0–65.5	65.0–65.5
RPM Tach/Edge Insight	1,700/1,677	1,700/1,680	1,700/1,677
Fuel used (gallons)	10.380	11.033	11.533
ECM indicated MPG	23.2	22.4	21.0
MPG calculated	21.45	20.18	19.30

The less aggressive Cooper A/T3 delivered much better mpg.

Tread Results Commentary

Choosing the Cooper S/T MAXX over the STT PRO mudder offers a 4.6% bump in fuel economy. Running the A/T3 instead of the S/T MAXX delivered a 6.3% increase. The leap from the STT PRO up to the A/T3 is 11.1%. Wow!

It’s impressive that a modified, heavy-duty, 4WD pickup with prodigious capabilities, weighing 8,900 pounds empty, with 34” x 12” tires mounted, can still reach or exceed 20 mpg during highway travel. Obviously most driving involves at least a few and stops and starts, but these repeatable tests demonstrate what is possible if speed and idling are minimized. If I picked the Discoverer A/T3, it appears that long distance highway runs, even with a couple pit stops, could top 20 mpg.

If one needs the extra grip offered by the STT PRO or S/T MAXX, choosing the A/T3 all-terrain might not be an acceptable tradeoff. Yet, if one is so inclined and has the space, these numbers seem to reinforce the practice of having two sets of tires and wheels. Whether they are all-terrains and mudders for your truck, or highway and winter rubber for your car, strong arguments can be made about picking the right tool for the job. We don’t wear flip-flops to go mountain climbing, and our clodhoppers are out of place in a gymnasium.

Off-highway traction is great with a mudder, but you will pay at the pump.

Does Width Matter?

The initial primary platform for measuring how tread width affects mpg was my modified, heavy, and low-geared ‘06 V8 4Runner, because I already had one of two desirable sizes. One might think the results would be relevant for most light-truck platforms. The conditions and procedures were the same as those for the different tread patterns.

I used Cooper’s S/T MAXX in 255/80R17, and 285/75R16, both 33” tall, but the 285s are substantially wider. The 255s are about 10” wide and the 285s about 11.5”; conventional wisdom says the 285s would consume about 1–2 mpg. Without creating another table, the short story is that theses tests delivered ambiguous results, there was very little difference. I was shocked! Followup runs might indicate these results were a fluke, but there were no obviously problems or procedure inconsistencies. The narrower 255s delivered 18.34 mpg, and the 285s 18.22 mpg.

I thought wider treads consumed more fuel, not so sure anymore.

On the car or dismounted, the 285s are much wider than 255s.

Ram Width Comparison

Two sets of tires and wheels for my ‘14 Ram partially met the width criteria, meaning they were very similar height with the identical tread pattern, yet the width difference was small. I had them, so test I did, using the same parameters, during the same week, weather conditions, etc.

One set were the 295/70R18 S/T MAXX in table one. The other were 285/75R17 S/T MAXX mounted on 2015 (WFV) forged aluminum Power Wagon wheels, which weigh 28.6 pounds each. These 285mm-wide Discoverers are also 34” tall, but just fractionally shorter than the 295s. The mounted, measured tread width difference between these two sets is only about 3/8”.

The seventeens were evaluated at the end of six consecutive days of testing, and the weather started to change, with 22 mph winds near the end of this last trip. This was noteworthy, but I’d argue that there was not enough wind during most the run to impact the outcome. The data appear to support that opinion. For the slight difference in width, the results appear appropriate. There simply was not enough difference to influence economy, 20.18 vs. 20.22 mpg. I call that a draw.

295/70R18 vs. 285/75R17. Not a huge width difference but still easy to see.

Forged 17” Power Wagon wheel on the left, forged 18” Bighorn wheel the right.

Table Three, 285/75R17 Measurements

Cooper Discoverer 285/75R17	S/T MAXX
Weight	64
Weight mounted lb.	93.4
Height unmounted	33 11/16”
Height mounted @60	34”
Tread width	9 1/4”
Tread depth	18.5/32”

Table Four, Ram Width Matters 285/75R17

Width Matters MPG	S/T MAXX 285/75R17
Test GVW lb.	8,900
Tire PSI F/R	60/40
Date	9-30-16
Time	0759–1130
Temperatures F	55-59-69-71-73
Wind/Gusts	0/0-3/4-5/5-5/14-22/22
Odometer	27,780–28,000
Trip Odometer	219.0
Odo error % MM & GPS	1.57/1.68
GPS miles	222.7
MPH indicated	64
MPH GPS	65.2–65.7
RPM Tach/Edge Insight	1,700/1,690
Fuel gallons used	11.011
ECM indicated MPG	20.9
MPG calculated	20.22

Good traction with a tolerable mpg penalty, I prefer a hybrid/commercial traction tires like the Discoverer S/T MAXX.

The Ram results were not a big surprise. The lack of separation between the 4Runner’s width test mpg numbers, and to a lessor extent the Ram’s, have me questioning how much tread width alone impacts fuel economy. Much taller tires, with the corresponding overall gearing changes, combined with more aggressive tread patterns may be the main story behind fuel economy losses when fitting aftermarket rubber. Sometimes testing answers questions.

James Langan

A version of this article was also published in the Turbo Diesel Register magazine.

Source:

Cooper Tires: coopertire.com

September 1, 2017January 14, 2019

Load Range F Toyos, a 1,700 mile evaluation

Toyo’s New Load Range ***F*** Open Country Tire Line

Toyo’s new load range *F* LT tires. Using ‘em hard.

Backgrounder

Torque, horsepower, and tow/haul ratings in our so-called light-trucks have been soaring toward the stratosphere for several years. The competition between the North American diesel pickup manufactures to one-up the other has never been stronger. They have passed the 900 lb-ft barrier and are marching toward the next big hurdle; 1,000 lb-ft of flywheel torque. (At least that is the number on-paper, torque management can make it feel like less, but the idea is to prevent unnecessary roughness and increase driveline longevity.)

In decades past the transmissions, brakes, frames, and other items didn’t match the grunt of the medium-duty truck engines stuffed into pickups, but those inadequacies are mostly behind us. The constant improvement of these components could not support the increased ratings if light-truck (LT) tire capacities didn’t keep pace. There is possibly nothing less safe than not having enough tire (capacity, speed ratings, etc.) for the job. Manufacturers continually strive to meet market demands. If we ask for and buy, companies are happy to build stuff for us.

More Air For Big Loads

There is science and some regulating body input that affects how much tires are rated to support. A simple way to think about tire capacities is to understand that it is the total amount of air inside a tire that supports the rated weight. That includes the physical volume/space inside the tire and the air-pressure. A tire of a given size that can accept higher pressures, is almost always going to be rated to carry more mass. More space and more psi equals more capacity in pounds.

As simple as we try to make this, there is at least one combination of ratings that many find illogical. Most, but not all, load range (LR) E LT rubber carry their maximum rated loads at 80 psi, but a few are rated for a maximum of 65 psi. In addition to not supporting as much cargo, because of the lower pressure, trucks with a simple TPMS (tire pressure monitoring system), like a late model 2500 Ram/Cummins, will always have a TPMS warning light illuminated when running with less than the maximum 80 psi in the rear tires and/or 60 psi up front.

The TRA Sets The Standards

The Tire and Rim Association (TRA) is the standardization body for this industry in the United States. It was established in 1903, and it is lead by top technical representatives from member companies. There are a few niche manufacturers who don’t belong to this association, and therefore may not abide by the industry standards, but they are few. The common tire sizes, load ratings, and capacities most of us use and are familiar with were created and sanctioned by the TRA. Traditionally, flotation sizes (33×12.50R17, 35×12.50R18, etc.) have received more conservative ratings, notably lower than those for LT-metric sizes. Why? Because the TRA says so. Maybe there is a technical and/or regulatory reason, but for the end user they are what they are, and we must pick a tire the meets our needs.

Load range *F* 35×12.50R18 handles 3,970# at 80 psi.

New Load Range F Toyo Tires

Toyo Tires is again leading the industry by introducing load range F tires in sizes that were formerly 65 psi, load range E. Toyo is making several in their Open Country A/T II and M/T designs, plus a couple for Open Country R/T. Toyo’s sister company Nitto was actually first to market with LR F light-truck rubber last year, but they are only offered in a few part numbers in one tread pattern, the Nitto Ridge Grappler.

Nearly all of the new LR F products added to the Open Country line are in flotation sizes, instead of LT-metric. Two 35” tall examples of these different size formats are the LT305/70R18 LT-metric, and the 35×12.50R18LT flotation size. Both are roughly 35” tall by 12.5” wide, and made for 18” wheels. All of the new Toyo LR F sizes listed here are for taller, 18”, 20”, and 22” wheels.

Open Country M/T

33X12.50R18LT

35X12.50R18LT

LT305/55R20

33X12.50R20LT

35X12.50R20LT

35X13.50R20LT

33X12.50R22LT

35X12.50R22LT

37X12.50R22LT

Open Country R/T

LT305/55R20

35X12.50R20LT

Open Country A/T II

33X12.50R18LT

35X12.50R18LT

33X12.50R20LT

35X12.50R20LT

35X13.50R20LT

33X12.50R22LT

35X12.50R22LT

37X12.50R22LT

Toyo A/T II Xtreme, 35×12.50R18, 68#, not yet mated to wheels.

Time To Think Differently About Tires. Use The Load Index

The load range letter designations will surely continue, but they are a somewhat confusing standard because the psi and LR are not married like most consumers think, they’re merely going steady but occasionally flirt around. The older ply rating (or P.R.) standard is still used, and this is stamped on the sidewalls of many tires (i.e. 6-ply rating = LR C, 8-ply rating = LR D, and 10-ply rating = LR E) and is arguably irrelevant in the 21st century. The numbers do not mean a tire has that many body plies; they don’t. This is a holdover from the old bias-ply days, where the number of cotton carcass (body) plies helped increase the capacity. Tire technology has advanced a bit over the past several decades, and cotton plies are no longer used. If the ply rating designations are outdated and the load range letters can be misleading or confusing, what should we use? One tire engineer acquaintance suggests we use the load index, and I’m inclined to agree.

Size, load index (128), speed rating (Q), and 12 ply rating.

The load index is a number that indicates the maximum weight a tire can support when properly inflated to its maximum cold psi, and it is stamped on the sidewall like the other ratings and information. Using the load index, and/or the tire inflation charts that I’ve favored for over 20 years, removes much of the potential confusion, as it focuses on how much is supported at what psi. My push to start using the load index over (or in addition to) these older metrics starts here. It will be an adjustment.

35X12.50R18LT Toyo Open Country A/T II Xtreme

My 2014, 25th Anniversary Cummins Turbo Diesel routinely operates at its GVWR, so I welcomed the additional capacity of the new load range F rubber. As a fan of shorter and narrower wheels, I chose the Open Country A/T II Xtreme pattern in a 35×12.50R18LT. With the new load range F/12-ply rating, each tire is rated to carry 3,970 pounds at 80 psi. The load index is 128, the speed rating is Q, tread depth is 17/32”, and each tire weighs 68 pounds.

For comparison, the 35×12.50R18 load range E A/T II has a load index of 123, which is 3,415 pounds at 65 psi. Increasing the maximum load by 555 pounds per tire is a big deal, and it is necessary for fans of big wheels and flotation sizes that haul heavy stuff.

The Xtreme Toyos have decent void for a 5-rib all-terrain.

Perfect Balance

Toyo prides itself on making exceptionally high-quality tires that often require relatively little wheel weight to balance. This is not just a claim; it has been confirmed by Toyos I’ve tested. Mounted on 32-pound Ram Laramie WBL aluminum wheels, the tread width is 10.25”, and the combination weighed 100.6 pounds on my shop scale. Using the dynamic, dual-plane balancing method, they took the following ounces to balance:

Outside Inside Total

#1 0.5 0.75 1.25

#2 2.0 0 2.0

#3 1.75 0.5 2.25

#4 2.00 1.5 3.50

“The New Dodge, America’s Truck Stop”, old-school measuring tool.

Dynamic balancing always requires more weight because the tires and wheels are balanced in two planes, vertical and horizontal, instead of just vertical (the so-called static method). For these tall, wide, and heavy tires and wheels to require so little lead is impressive. Four tries requiring so little weight is what one might hope for when using the static method for a smaller, lighter tire and wheel package. Even doubling the numbers here would not be unreasonable for static balancing. Awesome Toyo!

WBL Laramie wheels are slightly narrow, 8” vs. the 8.5” minimum recommended width for a 35×12.50R18 tire. They seem fine.

First Short Drives

Keeping the balancing data in-mind, it was no surprise that these Toyos were as smooth as glass at any speed on a good roadway. What about the difference between these new LR F Toyos compared to the same tire in a LR E? When I shared with friends I was running new LR F tires, a couple asked about the ride, assuming they would be stiff.

Ride feel is appropriate, no stiffer or sloppier than a typical LR E 80 psi tire. Running 60 psi in front and 80 psi in the rear—the same as most other tires and sizes on my Ram when fully loaded—the truck is as smooth and stable as it would be with any 80 psi tire.

The rugged and familiar 3-ply sidewalls and 7-ply tread of most Toyo Open Country LT designs felt just right. The obvious advantage of the new LR F is being able to carry more weight (load index 128) and not having a TPMS light illuminated when pumped-up to higher pressures.

Humboldt-Toiyabe National Forest, east of the Big Smoky Valley, Nevada.

Long Haul — A Quick 1,700 Miles

These new 35×12.50R18 Toyos were mounted just days before driving from Reno, Nevada, to Flagstaff, Arizona, for the Overland Expo West event. Driving conditions and surfaces included a little city, plenty of high-speed Interstate freeway, winding rural highways, some rain, dirt and gravel roads, and even a bit of snow.

The Toyo A/T II is mud + snow rated, and does well in snow.

The audible hum emanating from the Xtreme version of Toyo’s A/T II may surprise the uninitiated, but this 5-rib tread has a fairly open pattern for an all-terrain. The voids needed to help evacuate rain, snow, slush, moderate mud, and other debris, will make any tire louder than a less aggressive design. Of course the roadway surface makes a difference, tires typically sing more on concrete than asphalt, and the slightly wider (than I usually run) 12.5” meats put extra rubber on the road. The tires are not loud by traction tire standards, but you can hear them, and as I headed for the Southwest, the title track from Steve Earl’s 1986 debut album, Guitar Town, started playing on my radio, including:

“Hey pretty baby don’t you know it ain’t my fault

I love to hear the steel belts hummin’ on the asphalt…”

Being familiar with the tread, there were no surprises; the tires handled varied terrain well, as expected. I’ve run the Toyo A/T II Xtremes before, and was happy to evaluate them again.

James Langan

This article was also published in the Turbo Diesel Register magazine.

Sources:

Toyo Tires: toyotires.com

April 11, 2017September 1, 2017

Toyo Introduces Load Range F Light Truck Tires

Link: Toyo LR ~F~ 1,700 Mile Evaluation

New load range F flotation sizes in the Toyo Open County M/T, R/T, and A/T II tire lines!

Toyo Open Country M/T, load range F, 12-py rating, 35×12.50R18

This is big news! Torque and power ratings continue climbing in new heavy-duty pickups, which are capable of hauling and pulling massive loads.

RoadTraveler.net will be reviewing a set as soon as possible.

TOYO LR F embargoed

March 15, 2017March 24, 2017

Traction Tires from the 2016 SEMA Show

A few tires that got my attention at the 2016 SEMA Show.

Cooper Discoverer STT PRO in 40×13.50R17LT

Cooper STT PRO 40”

We really live in a super-sized America, maybe world? Tires that would have been almost monster truck worthy a few decades ago are now produced in highway-rated, easy to balance radial designs. Cooper introduced their fantastically rugged, yet tame on-road, Discoverer STT PRO in a new 40×13.50R17LT size.

Cooper has manufactured 40” tires for subsidiary and private label brands; however, this is the first to wear the flagship Cooper name. Two other big sizes were introduced, the 38×15.50R18 and 38×15.50R20. As sizable as these may sound, 35×12.50” tires can be fitted to Fourth Generation Ram Cummins Turbo Diesels with no lift, stock wheels, and only minimal rubbing. coopertire.com

Mastercraft CXT, a new commercial traction design

Mastercraft Courser CXT

This past summer Cooper subsidiary Mastercraft introduced their latest commercial traction tire, the Courser CXT. The CXT features: variable full-depth siping, silica-rich compound for wet/winter traction (M+S rated), large scallops on the outer lugs and generous sidewall shoulder rubber. They are available in 29 sizes, each with a generous 18.5/32” tread depth. A friend and I have been logging miles on a set, accumulating wear data from two Ram/Cummins trucks. mastercrafttires.com

Detailed look at the Mastercraft Courser CXT: Mastercraft CXT part one

Mickey Thompson

Mickey Thompson introduced the Deegan 38 All-Terrain for wheels from 15” to 22”. Twenty-nine sizes are available now, with two more coming in April, and the final two sometime in the second quarter of 2017. Light-truck sizes come with a 55,000-mile tread-wear warranty, and P-metric sizes have a 60,000-mile tread-wear warranty. Mickey Thompson says the new design features a “silica-reinforced compound and special siping for great traction, superior cut and chip resistance, and excellent handling and braking in wet and off-road conditions. Tread element tie bars enhance stability and responsive handling on changing road conditions. Angled shoulder scallops and aggressive two-pitch SideBiter’s enhance traction.” mickeythompsontires.com

Nitto Ridge Grappler

The newest LT design from Nitto looks like a winner. A hybrid all-terrain with traction lugs for the outer ribs and a slightly lower-void center, it looks like noise should be well controlled. The shoulder tread is beefy, and, as with all Nitto LT tires, there is a different design on each side; you choose. Several sizes are made for 17” to 22” wheels. nittotire.com

Toyo’s Open Country C/T mountain-snowflake rated

Toyo C/T

Manufactures are offering enthusiasts traction tires that are much quieter and less aggressive than mudders but with superior all-weather traction characteristics over a traditional all-terrain or all-season. Toyo eliminated all doubt about the target market by putting it right in the name; C/T stands for commercial traction. The Toyo Open Country C/T was originally only available in Canada, but it was released for sale in the USA in 2016. The C/T meets the mountain snowflake/Alpine severe winter spin-up test requirements. toyotires.com

January 4, 2017March 28, 2019

Mastercraft Courser CXT

Commercial Traction

Most light-truck tires are welcome in my garage, from tame all-terrains to the impressively streetable modern mudder. However, I have a strong preference for rubber that fit neither category, those that intentionally blur the lines of distinction, finding their own focus. Known by their traditional name, commercial traction tires, or aggressive all-terrains, hybrid, or the newer slang moniker, tweener (in-between), the design goal is similar.

Commercial traction tires are not new, they have been produced for decades, though the choices were fewer and they rarely received much marketing budget. Still not necessarily the beneficiary of the biggest advertising campaigns, depending on the brand, the performance advantages of modern hybrid treads have won-over many enthusiasts as a practical choice with fewer compromises. This segment of the market demands good grip on multiple surfaces, load-carrying capability, and puncture resistance.

Notably better in sloppy stuff than a typical all-terrain, with less noise and superior versatility than muds, there is much to like. Some have more sipes and the 3-peak/snowflake winter rating, while many don’t, but still perform well in the wet stuff. Nearly all have prodigious tread depth and void—particularly at the outer lugs—that broadcast their ability to absorb and fling muck when required. Mud-terrains are often described as 20/80-designs (20% road 80% dirt/mud), but commercial tractions are generally 60/40, 50/50, or 40/60, depending on their characteristics.

Mastercraft Courser CXT

In May 2016, Mastercraft Tires introduced their new light-truck (LT) commercial traction tire, the Courser CXT. It’s a mid-void, 4-rib that replaces the Courser C/T (C/T = commercial traction). Mastercraft is a subsidiary of the Cooper Tire & Rubber Company, one of the few remaining American tire companies and manufacturers. Before sharing my observations and insights, what Mastercraft says about their product is quoted below in orange:

Overview

The Courser CXT was designed as a premium light truck commercial traction tire that provides trusted all-terrain performance with enhanced off-road durability. The CXT features variable full depth siping and a silica rich tread compound for enhanced wet and winter traction. The large tread element and blocky design help to resist abnormal wear while enhancing tread stability and durability.

Large Surface Area Tread Blocks

Provide increased grip on and off-road while improving wear performance.

Optimized Void-to-Rubber Ratio

The amount of rubber on the road is optimized to provide rough terrain traction and enhance on highway driving comfort and feel.

Enhanced Upper Sidewall Design

The shoulder design increases off-road traction with side traction blocks and the circumferential raised rubber feature protects against sidewall abrasion and impacts.

Large Shoulder Scallops

The scallops provide a “mud-scoop” effect for dependable off-road traction while giving the CXT a more aggressive look, to enhance the appearance of almost any light truck vehicle.

M+S Rated

Extra Tidbits

The CXT is offered in 29 sizes, starting with the oldie-but-goodie 31×10.50R15LT, up to the 35×12.50R20LT. The size breakdown includes three 15-inch (all load-range-C), nine 16-inch, nine 17-inch, five 18-inch, and three 20-inch sizes. All sport a substantial 18.5/32-inches of tread depth, offering potentially more grip and longevity than others that start with less. In addition to the M+S rating, the CXT can be studded.

For those familiar with Cooper’s other LT designs, it is easy to assume that the CXT is simply a different tread slapped onto their extremely popular and capable, Discoverer S/T MAXX casing. Not so, they are different tires, both tread and carcass. Yet, many considering the CXT will likely also consider the S/T MAXX.

Mastercraft CXT vs. Cooper S/T MAXX—Two Primary Differences

The Discoverer S/T MAXX employs Cooper’s Armor-Tek3 carcass, a 3-ply sidewall, whereas the Courser CXT uses a 2-ply design. There are pluses and minus to both depending on one’s needs; 3-ply sidewalls are generally more rugged and stiffer, where a 2-ply may flex better, ride softer, and weigh slightly less.

The S/T MAXX is optimized for severe cut and chip resistance. When the MAXX was added to Cooper’s light-truck line it’s closest sibling was the S/T (no MAXX), which was/is not nearly as cut and chip resistant. The Discoverer S/T is also a straight 4-rib, where the MAXX’s center alternates between four and five.

Tread and sidewall specifications for a CXT 255/80R17E

255/80R17 Cooper Discoverer S/T MAXX and Mastercraft Courser CXT

The CXT has extra silica for additional wet traction. The slightly higher-void of the 4-rib CXT is visually similar to the older Cooper S/T, but the CXT has deeper scalloped outer lugs, plus beefy upper-sidewall (shoulder) tread that the older S/T does not.

More or slightly less void, 2-ply or 3-ply sidewalls, increased wet traction potential or optimized cut and chip resistance…only you can decide.

Outer rib tread lugs—Cooper S/T MAXX, Mastercraft CXT

Cult Of The 255 / The Third 255/80R17

Several of the 29 Mastercraft Courser CXT sizes could fit one of my vehicles, and I was tempted to pick a larger size. However, for nearly two decades I’ve run and been a fan of moderate width tires, chiefly the 255/85R16, and for a few years its 17-inch brother, the 255/80R17. Mastercraft makes the CXT in both of these sizes, and 255/8x aficionados are surely rejoicing!

One challenge for those wanting to move to the 255/85 size is the lack of treads with less void; many current 255/85R16 offerings are mud-terrains. The 255/85 has become a niche choice, with few newer trucks using 16-inch wheels. The 255/80R17 is even more specialized. Mastercraft’s introduction of the CXT raises the total number of tires offered in this size to three. Cooper makes two of them; BF Goodrich’s mudder is their only competition.

Height, Weight, Width

A super-clean set of fourth-generation Ram 17×8-inch WFK forged-aluminum wheels were purchased from a Craigslist seller, each weighing just 21.8 pounds with the hubcap. Unmounted, a 255/80R17 CXT registers 55.2 pounds on my shop scale (the same size S/T MAXX is 58 lb.), and once mated to a WFK wheel the combination measured 77.2 pounds. Inflated to the maximum 80 psi, the overall height was 32 15/16-inches, with 8-inches of tread.

It’s noteworthy that I’ve repeatedly found published specifications for Cooper-manufactured tires to be accurate. For this tire and size, on a 7-inch wheel, Mastercraft lists overall diameter of 33.15-inches, and tread width of 8.07-inches. Acknowledging that manufacturers’ measuring tools are likely more accurate than my straightedge and yardstick method, and the 255/80 CXT was mounted on a wider wheel, my measurements were still within nearly two-tenths. For the curious, the unmounted height was almost a half-inch shorter, but focusing on unmounted diameter is pointless: tires are not used without wheels and compressed air.

CXT 255/80R17E tread width is eight inches, both unmounted and mounted

Mounting And Balancing

Manufacturing tolerances, weight, width, construction, and the wheel employed all affect how easily and well an assembly is balanced. In general, smaller and lighter equals easier to true. Using the static, single-plane method, the ounces of wheel weight required were:

#1 3.50

#2 2.75

#3 2.50

#4 4.50

Discount Tire has been mounting and balancing my tires lately

Modern spin balancing is quite good. Single plane, “static” balancing was chosen

First Drive

The tires were immediately put to work supporting a maximum load on a built Ram that typically lives at its 10,000-pound Gross Vehicle Weight Rating (GVWR), carrying a Hallmark Milner camper, tools, and other supplies. With the fronts at 60 psi and the rears at 80 psi, the ride was neither mushy nor harsh. Over a familiar section of freeway where expansion joints can induce freeway hop (generally not a problem on this truck) the CXTs exhibited no such tendency. Steering response was excellent, a common trait with narrower tires, as they take less energy, time, and effort to change direction. Even at paralegal speeds, balance didn’t change and no bad-vibrations were felt.

Noise

Initial impressions were that noise is slightly more than the popular Cooper S/T MAXX, which is an impressively quiet design. This is not surprising as the CXT has a higher-void, 4-rib pattern instead of the MAXX 4/5-rib. The volume and deeper tone is not annoying or loud, and what I expected; both are certainly much quieter than any mud-terrain. The CXT sounds similar but slightly quieter than the older Cooper Discoverer S/T (not to be confused with the S/T MAXX, STT or STT PRO).

Appearance

Function is more important than form, but many like their 4WDs to look tough. Before receiving this set of Mastercrafts I’d not seen the tire in person, just the few marketing shots online. There were no substantive professional reviews or user reports. This article still may be the first. The outer lug scallops were a pleasant surprise, and the sidewall shoulder tread was beefier than I expected. Pretty sexy, in a nice, girl-next-door way.

An OEM 17″ WFK forged aluminum wheel and a 255/80R17 Mastercraft CXT are a light tire and wheel combo, only 77.2 pounds

Notes On Tracking

When changing to a different tread, size, and/or wheel, there is a possibility that your vehicle may need a custom alignment to match the new combination to the chassis. Some folks are willing to ignore a little drift (or pull) right or left, where others find any drift unacceptable. Some tires have a well-deserved reputation for directing vehicles to the shoulder or median, but different trucks and roads can cause different behaviors.

If your truck has an independent-front-suspension (IFS), adjusting the caster (and to a lesser extent camber) to help it track straight should be easy for a good alignment shop willing to make custom adjustments. Be willing to pay more. Finding such an establishment with a skilled technician may be challenging. Many places that should know better still want to use the factory geometry for modified rigs when different settings would fix or dramatically improve drivability.

Picking My Own Line

The 2014 Ram initial CXT test platform has a Specialty Products Company (SPC) 1.5-degree offset ball joint at the right-front, installed after only 1,500 miles to counteract the characteristic right-pull of many Ram trucks and/or some tires. Before any modifications, still running the stock Firestone highway treads, this truck drifted right and would head for the shoulder quite rapidly if the steering wheel was released, typically in six seconds or less. Unacceptable.

The SPC offset ball joint increased caster angle on the right, effectively directing the truck left helping the chassis drive straight without input from the driver to correct the right drift. With such an aggressive geometry modification there is always the possibility, even likelihood, that the truck will track left with some tires or under certain circumstances, including differing road crown. This was a compromise I was willing to live with, but it’s not for everyone. Swapping ball joints is not a trivial affair on a live-axle truck.

With the CXTs mounted, this truck has a slight tendency to go left, depending on the roadway. However, three “look mom, no-hands” tests during the first 100 miles, under suboptimal windy freeway conditions, achieved 12.06, 11.90, and 12.26 seconds before semi-autonomous driving had to be curtailed to prevent the truck from changing lanes. These are good numbers, but not surprising as narrower treads generally track (much) better than wide ones. This also means I’d be perfectly happy to run these on long road trips. The stars were aligned during another test on Interstate 5 in California where I clocked 25 seconds of straight tracking. A buddy’s Dodge that drifts right with most tires, still did with the CXTs mounted . Your truck may vary; adjust as needed.

No complaints after the first few thousand miles

Sources:

Cooper Tire & Rubber: coopertire.com

Mastercraft Tires: mastercrafttires.com

Specialty Products Company: spcalignment.com

November 25, 2016November 25, 2016

Cooper Discoverer S/T MAXX 295/70R18 and 285/75R17

Cooper Discoverer S/T MAXX. Left 295/70R18 Right 285/75R17. Both 34-inches tall. — Cooper Discoverer S/T MAXX—Left 295/70R18— Right 285/75R17—Both 34-inches tall

My idea of a good time on Black Friday? Playing with black tires in my shop of course.

After a 2,500 mile break-in, the 285/75R17 Cooper Discoverer S/T MAXX on 2016 Ram Power Wagon WFV wheels were removed. They were replaced with 295/70R18 S/T MAXX on forged WBJ OE 18-inch wheels.

Aside from the wheel diameters, these tires and wheels are very similar. However, there is a noticeable and measurable height and width difference, the 295s being both a bit wider and taller.

Multi-tread and width tests are underway for future editorials.

October 6, 2016May 10, 2018

Cooper Discoverer A/T3

Testing & Talkin’ Tires

October 6, 2016

Even casual readers of this site will notice that I’m a light-truck tire aficionado; there are many posts about rubber for light-trucks. My personal obsession aside, there are powerful reasons tires are such a popular topic for both writers and enthusiasts nearly everywhere we gather. Mounting new meats is one of the easiest and most dramatic performance and/or appearance modifications owners can make to their trucks. Replacing worn rubber with new, even the same pattern, can greatly improve safety and traction. If you have any doubts, watch this Tire Rack video regarding tread depth and stopping distances on wet roads: tirerack.com/videos/index.jsp?video=5&tab=tires

Looking through a historical lens, modern tires are generally excellent, with unsurpassed designs and sizing options, and they are a good value. Yet value doesn’t mean inexpensive, and depending on the size and performance category, a new set of shoes for your truck can easily top $1000. This substantial outlay leads to questions and much research for many buyers.

Still Plays With TIRES means frequent trips to tire stores with a few shoes and insoles. This is a moderate load, sometimes I need a bigger trailer.

Journalism’s Dirty Tire Secret

If you read truck tire reviews critically, you may realize that many involve very few miles of use before the evaluation is penned, often as little as a few hundred miles. Reasons for this include the long lead-time for print periodicals, editors’ desire to publish something as quickly as possible, and sometimes a little pressure from the manufacturer or advertising agency folks. Writers sometimes mount new tread and take them on a little excursion, writing much about the adventure and some about the tires, then use this one experience as the appetizer, main course, and dessert. Meh.

Another favorite is the manufacturer’s initial ride-and-drive test at a testing facility or track. When possible I happily attend and enjoy such events, but they are mostly a good introduction. If they’re not followed with a longer, personal-use test, they often don’t tell the complete story.

When one brand redesigned their super-popular all-terrain pattern two years ago, they hosted journalists in Baja where the test vehicles were race buggies and Ford Raptors. I have no doubt that the conditions and obstacles were gnarly, and I’m not saying the product isn’t good. But how does one test a tire’s performance on an unfamiliar chassis, particularly on a race buggy or (factory) desert-prerunner truck? Where is the baseline? Are the tires being tested, or is the complete chassis? Would these highly-capable vehicles perform impressively if another tire brand or design was mounted? Surely.

Hopefully readers can benefit from my continuous evaluations. Instead of buying a new set every few years like many consumers, some running the same or similar treads repeatedly, I typically test a few sets each year. My personal experience and database over the past two decades is quite large, and includes aggressive mud tires, tame all-terrains, and many in-between. Although I swap tread often, I dismount them from wheels infrequently. At any given time I have several sets of tires on OE wheels, currently six that fit my 2014 Ram 2500, and keep notes on the dates, miles, performance, and wear. Some I buy, and some are supplied by manufacturers for review. Just this week I sold two older sets, one Ram and one Toyota, and bought a new set for my 2500. Some get more miles than others, depending on my needs and preferences, the physical size or fit, and how well they mesh with current objectives, but all receive thousands not hundreds of miles. Several years ago a teasing friend dubbed me “the Imelda Marcos of tires.” What can I say, if the shoe fits….

Starting lineup. There are few truck parts (any?) I like more than a fresh set of rubber. — There are few truck parts (any?) I like more than a fresh set of rubber.

Cooper Discoverer A/T3

Over the past several years Cooper Tire and Rubber—which is still a U.S.-based company and manufacturer—revamped their light-truck line. The 5-rib all-terrain Cooper Discover A/T3 is a natural choice for someone wanting better traction in more varied conditions than a highway tire (HT) offers, but something quieter, smoother and softer than a commercial traction pattern like Cooper’s S/T MAXX (which I’ve run on my 4Runner for a few years). The performance improvement over an HT can be substantial in inclement weather, including something as common as a hard rain, but the differences can be even more dramatic with a little snow, slush, or ice covering the roadway.

Because the A/T3 is their flagship all-terrain tire there are an impressive 56 sizes. The outer rib’s open lugs allow liquid and debris to escape better than highway designs, as do the circumferential voids in the center. The silica-based compound improves wet traction and on-highway handling, provides cut and chip resistance on rough terrain, and reduces rolling resistance. Lateral groove protectors reduce stone retention and drilling, and the broken center rib is designed to improve soft surface traction. It is M+S rated, and has a 55,000 mile tread wear warranty.

There will always be a place in my heart and space in my garage for high-void traction tires, though maturing has made me increasingly less fond of louder designs when they are not necessary. The A/T3 is pleasant, barely audible to my ears, and notably quieter than the similar but slightly higher-void 5-rib Toyo A/T II tested on my Ram for 8,000 miles. (The Toyos averaged 1/32 of wear for every 2,100 miles, with frequent rotations, and were removed to mount the A/T3s.)

Comparing Cooper’s high-void, 295/70R18E STT PRO mudder to the the 285/75R18E A/T3. Both sizes support 4,080# each at 80 psi.

Again I chose the fantastic, niche, LT285/75R18 size. Cooper is one of a handful of companies making this approximately 35×11.50 inch size, tall but not overly wide. These Coopers are 34.84-inches tall, with 17/32 of tread depth measuring 8.9-inches wide, and weighing 58.4-pounds solo and 90 when mated to Ram Big Horn WBJ forged aluminum wheels. They fit perfectly on the stock 8-inch wheels, and like any pattern in this size, will support a massive 4,080 pounds at 80 psi. Loaded to the Ram’s GVWR, with 60 psi in front and 80 psi in back, the rear differential ground clearance is 8 3/4 inches.

Balancing Act

Using my favorite local Discount Tire store the Coopers were dynamically (dual-plane) balanced. As always Centramatics balancers work in the background, adjusting to any irregularities on-the-fly. The A/T3s took very little wheel weight to balance, and they have remained smooth at all speeds, legal and above.

Inside Outside

#1 3.00 0.25

#2 1.75 1.75

#3 1.50 3.00

#4 1.25 3.00

The LT285/75R18E Discoverer A/T3 starts with 17/32” of tread. — The LT285/75R18E Discoverer A/T3 starts with 17/32 of tread.

Ride quality is smooth and compliant; the traditional construction 2-ply sidewall is not stiff, and helps absorb impacts, even at full pressure under a maximum load. The generous and squiggly shape of the siping helps grip, and is surely behind some of the excellent winter traction endorsements I’ve read on snow plowing sites (my A/T3s have not seen much wet yet). Straight-line tracking is good as one would expect from a 5-rib all-terrain/all-season design, as is steering response. When conditions are right my truck will drive straight for 10 seconds or more with no input. It’s too early to report on wear, but after the first 2,500 miles, it looks mileage will be similar to the Toyo A/T II tires mentioned above.

The A/T3 doesn’t feature or need sidewall tread for its target market.

Supporting Documentation

Confidence in my prose is important, but I enjoy sharing others’ views when it helps make a point. Before accepting the Senior Editor post at OutdoorX4 magazine, I was a technical editor at Overland Journal (OJ) for a few years. For the Summer 2014 issue, OJ conducted a comprehensive, seven tread, all-terrain comparison which was later published online, and can be read at: expeditionportal.com/where-the-rubber-meets-the-road. The article is a good read for traction tire enthusiasts. The short version is that the Cooper Discoverer A/T3 won both prizes after all the tests were completed: the “Value Award” and “Editor’s Choice”.

For a less analytical but impressive amateur review, this YouTube link gives a snapshot of the A/T3’s winter performance potential. A competitor’s design with plenty of tread remaining cannot start up a snowy incline in 2WD, but with Cooper A/T3s mounted, the truck moves forward.

youtube.com/watch?v=m2OHErN5ZOI&app=desktop

If you are in the market for a traditional 5-rib all-terrain, but with an updated design and reputation for superior traction, consider the Cooper Discoverer A/T3.

Sources:

Cooper Tires: coopertire.com, 800-854-6288

A version of this article was published in Issue 93 of the Turbo Diesel Register magazine, in my Still Plays With Trucks column.

Tread Matters: Tire Selection and Fuel Economy

Link: Toyo LR ~F~ 1,700 Mile Evaluation

New ***load range F*** flotation sizes in the Toyo Open County M/T, R/T, and A/T II tire lines!

This is big news! Torque and power ratings continue climbing in new heavy-duty pickups, which are capable of hauling and pulling massive loads.

RoadTraveler.net will be reviewing a set as soon as possible.

A few tires that got my attention at the 2016 SEMA Show.

Mastercraft Courser CXT

New load range F flotation sizes in the Toyo Open County M/T, R/T, and A/T II tire lines!