Tread Matters: Tire Selection and Fuel Economy

2014 Ram mpg test platform.

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.

Worth $11.
Love knowing what it really weighs.

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.
Same GPS distance used for all runs.
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

Copyright James Langan/RoadTraveler/Turbo Diesel Register. All Rights Reserved.

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

Source:

Cooper Tires: coopertire.com

 

2 Low UnLoc From BD Diesel Performance

BD’s kit 1030705 2 Low UnLoc for late model Ram trucks

Installing BD Diesel Performance’s 2 Low UnLoc Differential Kit For Fourth Generation Rams

Moving Slower

Reversing and maneuvering large trucks, trailers, or other big outfits can be challenging and even stressful for those lacking skill or confidence. One way to mitigate the reduced visibility and risk of hitting something and causing property damage, or worse, is to move slowly. This is obvious to most everyone, yet the slowest transmission gears, first and reverse, are still tall for creeping around campsites, parking lots, and other narrow spaces. Adding grades and/or tight turns can increase the gearing deficiency. Excessive slipping of a clutch or loading of a torque converter is not a perfect solution, but sometimes a necessary evil. Done improperly with too much rpm, or repeatedly, wear or a mechanical failure may be the eventual reward.

Transfer Case Auxiliary Gearboxes

Four-wheel-drive (4WD) trucks have become extremely popular in recent decades, even with folks that rarely, if ever, venture off-pavement. The low gearing in most transfer cases lives a very lonely life. The point of low-range is to go slow in technical situations, with the added benefit (or impediment) of powering the front tires. Using low-range increases torque and helps the engine move loads at slower speeds, even at low idle. Some savvy and careful drivers will shift into 4WD-low to access the gears for backing and maneuvering, but this is not without consequence.

Traditional part-time transfer cases split engine torque equally between the front and rear axles and are designed for slippery surfaces. A slipping tire can release the inherent bind that occurs at the transfer case between the front and rear shafts. When used on high-traction surfaces that don’t allow dissipation, there is a possibility of drivetrain damage, though the risk is small if the steered tires remain straight and distances are short. Once the front tires are turned, which dramatically increases the need for differential action, drivetrain windup will result. This energy is transmitted to and felt in the steering wheel, which will move or jerk in the driver’s hands as the drivelines complain. (Full-time 4WD systems use a center differential, avoiding the conflict between the front and rear drive systems.)

Two-Wheel-Drive Low

When most 4WDs had manual-locking front hubs, simply keeping the hubs in their normal, unlocked position allowed shifting into low range without connecting the front wheels to the axles. This works, and I did it for decades. Drivers should be careful and smooth because all of the engine’s torque, now multiplied by the transfer-case gears, is going to only one driveshaft, not two.

Manual hubs on Dodge Turbo Diesels disappeared with the First Generation in 1993. Second Generation trucks have a vacuum-operated front axle disconnect system that allows a relatively simple bypass to use low-range 2WD. BD Diesel Performance still makes a kit for these Second Generation Dodge trucks. After Dodge eliminated the disconnect system in favor of constantly driving the front axles, no simple solution existed; the only real option was to add manual hubs. With the return of front axle disconnect on heavy-duty Rams in 2013, now electrically-activated, preventing 4WD from engaging while accessing the low-range gears is again easy.

DISCLAIMER—As always, use extreme care and (un)common sense. Operate all machinery with due care, while also accepting the inherent responsibility that comes with any modification. You may be your own warranty station.

2 Low UnLoc

Spring 2017, BD Diesel Performance introduced their two-wheel-drive low solution, the 2 Low UnLoc kit for 4WD 2009–2017 1500, 2014–2017 2500, and 2013–2017 3500 Rams. BD sent me one of the first units.

One end of the harness has two OEM-quality connectors that go inline at the Drivetrain Control Module, another has ports for the two included relays, and a third connects to the supplied switch. My friend Phil and I installed the kit on his 2014 2500 with 35,000 miles on the clock. He tows a 24-foot travel trailer.

Plug-and-play harness makes for an extremely easy installation

It’s So Easy

The 2 Low UnLoc for late-model axle disconnect trucks is a simple add-on. BD’s directions were followed almost to-the-letter because I found no way or need to improve the process. The one slight deviance was drilling the switch hole.

Removing three push-in retainers for the carpeted panel below the glove box allows pulling the carpet rearward, which exposes the drivetrain control module. Unclipping the black plastic cover exposes the blue factory male connector that is replaced with BD’s. The OE male plug snaps into BD’s female connector. Re-clipping the drivetrain control module cover was only a minor struggle with the extra BD connector inside.

There is plenty of harness to locate the relays far from the drivetrain control module if desired, but we secured them below module with mounting tape. The last thing to do was to make a hole for the switch.

First step, remove carpeted panel below the glove box
Pulling the passenger side carpet exposes the drivetrain control module
BD’s harness placed inline at the drivetrain module

Pulling The Center Stack Cover

Removing the center dash cover that surrounds the radio and HVAC control is a simple task, though like doing anything for the first time there can be trepidation. The first step is the most critical and can be easily overlooked by the uninitiated.

A plastic liner snaps into the tray above the radio and must be removed to expose two TORX T20 screws. Remove these two screws first and replace last. The remainder of the piece is held with several snap-in clips, mostly around the perimeter, and it is simply pulled away at the edges. I use my fingertips and/or a plastic interior trim tool. After the surround is loose, a few connectors on the rear must be unclipped before the piece can be completely removed.

Drilling

Phil and I started this 2 Low UnLoc project by removing the dash center stack cover, which confirmed we could use the blank spot below the cubby on the right. From the front it appeared that the matching blank space on the left could be used instead. This was not the case on Phil’s truck, as there was a connector on the back. These little panels are great locations for switches, plus they are replaceable, secured with four Philips screws on the rear.

Rocker switch requires a large hole

BD recommends using a stepper drill bit to make the hole for their lighted rocker switch. I don’t own a stepper bit, but I would have been concerned about going too deep and making the hole too big. The largest bit in my toolbox is a 5/8”. After stepping up to this size we were close, but the hole was still slightly undersized. Carefully enlarging the hole with the same 5/8” bit worked; I stopped while the rocker was still a very tight, interference fit. A small file was used to cut a notch for the locating tab on the left side. Because of the snug fit, we were unable to use the 2WD LOW sticker BD provides with the kit.

Notched left side of hole for locating tab

Function Testing

Before pushing the rocker switch into its tight, final resting place we loosely connected the three color-coded wires and tested the 2 Low UnLoc system. The operating procedure requires rotating the rocker switch to the on position first, then moving the transfer case selector or lever to low-range. The red light on the rocker will illuminate, indicating that front axle engagement has been bypassed, and BD’s 2 Low UnLoc is active. To deactivate, the sequence is reversed; the transfer case is shifted back to two-wheel-drive high-range, then the switch is turned off.

Color-coded harness wires for the switch
After rotating the rocker, and shifting the transfer case, the switch light illuminates

We reassembled everything and tested the feature again. It worked. Phil and I both love the BD 2 Low UnLoc and think the $148 price is worth the functionality and ease of installation. Geno’s Garage stocks the 2 Low UnLoc kit, and reports they have been selling well.

James Langan

Copyright James Langan/RoadTraveler/Turbo Diesel Register. All Rights Reserved.

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

Sources:

BD Diesel Performance: dieselperformance.com, 800-887-5030

Geno’s Garage: genosgarage.com, 800-755-1715 

 

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.
Starting tread depth is 17/32”.

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.

Field testing in remote Nevada.
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.
Kingston Summit, Nevada, 8,680’.

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.

Copyright James Langan/RoadTraveler/Turbo Diesel Register. All Rights Reserved.

Sources: 

Toyo Tires: toyotires.com 

Overland Expo West 2017

Overland Expo West 2017 — Flagstaff’s Fort Tuthill County Park 

New Venue 

Overland Expo West is a three-day annual event focused on educating and inspiring folks to explore their outdoor world, both near and far. The big news for the event this year was change: it moved to a new venue, the Fort Tuthill County Park in Flagstaff, Arizona. The park offers about 30% more area and extra separation for truck and moto enthusiasts. There were over 200 classes, workshops, roundtable programs, and inspirational programs, as well as over 300 vendor booths. Fifty exhibitor spaces were added in 2017, with a waiting list for 2018, and there were about 2,000 additional attendees. The Overland Expo team is now focused on getting better, not bigger. Leading industry vendors and OEMs were present, including Ram and Cummins, which is where my coverage is focused.

Ram was a vendor again this year.
Cummins’ R2.8 Turbo Diesel attracted much attention.

There can be growing pains… I did overhear someone saying that the general, dispersed-camping areas were too tight and full. My sense is that overall this was a good move for the Arizona event, the growing tribe of overland travel enthusiasts and the vendors that are happy to accommodate their desires for comfortable, vehicle-supported travels and camping.

New Legend 4×4 Meets The Cummins 2.8L

New Legend 4×4, based in Iowa, has been doing impeccable restorations of vintage Scout II and Scout 800 bodies, mounting them on modern chassis, complete with high-performance engines, to give enthusiasts the joy of driving beautiful vintage iron without the poor drivability of vehicles built 50 years ago. They work hard to maintain the original vibe and hard-working focus of the old wagons, while tastefully blending it with modern performance, reliability, and safety. New Legend 4×4 works with their clients to create the ultimate mix of a vintage/modern vehicle. These rigs are meant to be driven, not be garage queens.

I’ve been an International Harvester fan since my youth, partially because my great uncle Clarence had a few, plus I’ve owned a ‘60s two-wheel-drive half-ton and two Scout IIs. The first, a Scout Terra pickup, was my first four-wheel-drive. The New Legend Scout IIs with V8s were very nice, but the rig that made me gaga was this 1967 Scout 800 with a Cummins R2.8 under the hood.

1967 Scout 800 on a Jeep Wrangler chassis.

The FIRST Production R2.8 Turbo Diesel

The Turbo Diesel Register readership needs no explanation as to why one might prefer to repower vintage iron with the new R2.8 Turbo Diesel instead of a gas V8. New Legend 4×4 was one of 25 beta test shops for the Cummins R2.8L in the U.S., and thanks to Steve Sanders at Cummins, they were lucky enough to receive the first production version of this new crate engine just in time to complete this Scout 800 and drive it to Overland Expo. Yes, they drove it from Iowa to Arizona, essentially non-stop, swapping drivers, with lots of coffee and Red Bull, with the blessing and encouragement of their customer as part of the initial shakedown. I interviewed Luke from New Legend to get the details on this beautiful build.

The Cummins R2.8 swap looks factory perfect.

This is a 1967 Scout 800, the body is original but “freshened”, which means cleaned, repaired, and painted to high standards. It sits on a new Jeep Wrangler Rubicon chassis, with the excellent and proven OE Dana 44 axles with electric lockers both front and rear. New Legend wisely didn’t try to invent new Wrangler suspension, instead they use AEV’s proven 2.5” system, which maintains factory geometry and drivability. Luke said, “it drives and handles amazingly”, like a brand new Jeep Wrangler JK, because that’s what is underneath. New Legend teamed with Duluth Pack in Minnesota, because they love Duluth’s made-in-USA waxed canvas, which really helps this particular Scout retain a vintage, rugged look and feel. Just what the customer wanted.

Modified and updated, the interior still looks ‘correct’.

The Cummins R2.8 has it’s own ECM, and Cummins makes it incredibly easy to connect the engine to the donor chassis, essentially just fuel and a few wires. The flier for the R2.8 Turbo Diesel inline 4-cylinder says it produces 267 lb-ft @ 1,500-3,000 rpm, and 161 hp @ 3,600 rpm, with an asterisk indicating “final ratings may vary”. The motor is connected to a NV3550, 5-speed manual tranny, which is backed by an Advanced Adapters Atlas II twin-stick transfer case. The base price for a build similar to this is about $100k, depending on how the customer specs their new vintage four-wheel-drive. Cummins was a vendor at the 2017 Overland Expo West gathering, primarily to support this fantastic, small, light, and powerful little engine. Smart move, as the repower opportunities look promising in this market segment.

American Expedition Vehicles 

American Expedition Vehicles (AEV) displayed their Prospector XL Tray Bed Edition, and the new Recruit, Ram 1500 package. The original Prospector XL was a personal project of AEV President, Dave Harriton, that was first displayed at the 2013 SEMA Show, and it has covered thousands of miles on- and off-highway since. AEV Special Operations is creating ten of these “Limited Edition, Unlimited Adventure” vehicles based on the regular-cab, long-bed, Ram 2500 platform. The trucks will feature their signature stamped-steel front bumper, DualSport suspension, lightweight aluminum bed, massive 41” tires, and more. The Prospector XL Tray Bed Package starts around $38,000, plus the base vehicle; I think they will sell all ten quickly.

Prospector XL Tray Bed from AEV.

The timing of this announcement is interesting, as I’ve been a fan of flatbeds since my commercial driving youth and my custom flatbed-equipped ’93 First Generation Turbo Diesel. For several months I’ve been trying to suppress my lust for a new regular cab, longbed truck…keep your eye on my column.

AEV’s Ram 1500 Recruit package.

AEV’s Recruit package for 1500 Rams includes a new 4” DualSport suspension for these independent front suspension (IFS) trucks. It increases wheel travel and off-highway performance, while optimizing the steering geometry for improved handling and reduced driver fatigue on-highway. The A206 T4 cast aluminum steering knuckles, new tie-rod ends, AEV-spec Bilstein 5100 series struts and shocks are key ingredients. Under the truck, a stamped-steel 4mm skid plate offers serious protection and maximum ground clearance.

The 4” DualSport suspension include a cast aluminum steering knuckle and upgraded tie rod ends.
Perfect, tight fit for the Recruit’s skid plate.

The Recruit’s heavy-duty grille conversion facilitates mounting their existing HD front bumper. Cast aluminum tow loops instead of the ductile iron pieces reduce weight, and their Heat Reduction Hood helps the Recruit look similar to the Prospector. New 18” AEV wheels are more versatile than the common 20” OEM rims. The Recruit package starts at $15,000.

AEV’s 18” aluminum wheels for Ram 1500.

AT Overland Habitat Truck Topper

The ingenious and detail-oriented folks at AT Overland introduced a version of their Habitat camper for full-size Tundra, F-150, and Ram pickups with both 5.5’ and 6.5’ beds; it was previously only available for mid-size trucks. The Habitat fills the void between a basic truck topper and a slide-in camper. The shell is made with lightweight aluminum and composites, is very robust, and has a base weight of only 340 pounds. Easily opened by one person, the 15’ long tent that deploys provides 96” of standing headroom near the tailgate when mounted on a Ram, and 85” at the front; plenty. When standing outside on the ground, the bed above acts like an awning.

The tent is made from a very durable, Teflon-impregnated, waterproof ripstop nylon (285 grams-per-meter), by American tent and camping gear manufacturer, NEMO Equipment. If customers chose a base camper ($8,800) without optional cabinetry, stove, or refrigerator and such, the camper does not reduce the hauling area of the pickup bed. The Habitat pictured here is on AT Overland co-owner Mario Donovan’s 2017 Ram 2500.

AT Overland’s Habitat topper tent for full-size trucks.
NEMO makes the tent for the AT Habitat.
Long and spacious inside a Habitat camper.

AeroContinental 

AeroContinental has started making chassis-mounted truck campers featuring stressed skin construction that are designed to be both attractive and field-repairable. Their first effort was on a Ford Super Duty, but their second is more appealing to TDR-minded folks, as it’s mounted atop a 2017 Ram 3500 with AEV’s Prospector package. It’s just waiting for a customer to spec the final layout inside. It makes me think of a vintage Avion camper, or Airstream trailer. “Aerospace meets overland” is one of AeroContinental’s tag lines.

AeroContinental prototype Ram camper.
Inside the AeroContinental.

ARB USA

ARB had three new items on display that caught my attention. The coolest being their new Elements Fridge ($1,300), designed to survive tough duty outside, like in a pickup bed. This weatherproof 12-volt compressor refrigerator (not just a cooler) features a stainless steel body and hinges, a gas strut that holds the lid in any position, a pin-code lock plus padlock hole, a light, and more. Once you start using a real refrigerator for camping or tailgating, it’s hard to leave home without one.

ARB’s new Elements refrigerator.

The ARB Adventure Light 600 provides up to 600 lumens of LED light ($59), with a lower 300-lumen setting. This portable light can be recharged by both AC/DC power, includes a battery-level indicator, has hooks and magnets, and is dust and rain resistant. There’s little question it’s rugged; one of ARB’s press photos shows a truck driving over the light.

Adventure Light 600.

Appropriate tire pressures are critical for performance and safety. Modern TPMS provide a safety net, but the best maintenance practices involve frequent use of a quality tire gauge. ARB’s Digital Tire Inflator ($55) has 23.5”, PVC-covered braided steel hose with a push-on chuck and valve clip, which reduces the need to squat or bend over while filling tires. The backlit LCD readout is protected with a rubber guard; it’s designed to read from 1-200 psi (0-14 Bar, 0-1400  Kpa); there’s a bleeder button and a 200-hour runtime from the two provided AAA batteries.

Digital Tire Inflator from ARB.

That’s all for this year, there was so much more, it would take 100 pages to cover it all. Check it out.

Copyright James Langan/RoadTraveler.net/PhotoWrite Intl. LLC.

All Rights Reserved. 

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

Sources:

AeroContinental: aero-continental.com 

AEV: aev-conversions.com 

ARB: arbusa.com

AT Overland: adventuretrailers.com 

Cummins: cummins.com 

NEMO Equipment: nemoequipment.com 

New Legend 4×4: newlegend4x4.com 

Overland Expo: overlandexpo.com 

Ram: ramtrucks.com 

Zamp Solar Flexi Flat 100 watt panels

Zamp Solar TDR96

 

Source: Zamp Solar, zampsolar.com

Copyright James Langan/RoadTraveler/Turbo Diesel Register magazine. All Rights Reserved.

AEV EcoDiesel 1500

AEV EcoDiesel 1500 prototype
America Expedition Vehicles’ EcoDiesel 1500

The enthusiasts at American Expedition Vehicles (AEV) have been focused on the heavy-duty Ram Cummins platforms in recent years, but they have now waved their magic wand over a 2017 1500 EcoDiesel. The results are easy on the eyes.

AEV’s modular Premium Front Bumper rides on a prototype AEV 4” DualSport suspension, with 325/60R20 BFG KO2 all-terrains on repainted 20” factory wheels. This is a tall wheel for AEV, who are fans of more tire and less wheel for off-highway performance, but the 35” height is moderate. I expect they will introduce a smaller wheel when the 1500 parts start flowing. A 2500 grille and AEV headlight filler panels were installed to facilitate fitting their Heat Reduction Hood, which is complemented by their Raised Air Intake. AEV’s Bed Rack and a James Baroud tent dress-up the rear.

The EcoDiesel 1500 was merely a prototype, though surely AEV was gauging interest in the 1500 platform for future offerings. For a 4WD that actually sees rugged off-highway use, the heavy-duty trucks are relatively tall, but the 1500s are low-riders. AEV’s treatment transforms the chassis…wonder how my Hallmark camper would look and work in the bed of an AEV-modded EcoDiesel? aev-conversions.com

Overland Eco-Diesel 1500 from AEV

American Expedition Vehicles: AEV-Conversions

Copyright James Langan/RoadTraveler. All Rights Reserved.

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