Firestone Destination M/T2 and Transforce AT2

Firestone’s new Destination M/T2

Firestone took a couple big steps forward this year by redesigning two of their light-truck tires that may appeal to the TDR audience: the Destination M/T2 and the Transforce AT2. The previous Destination M/T was a whopping 12-years old and needed an update; even Firestone admits it was very long-in-the-tooth. The new Destination M/T2 retains some family heritage, but the tread, particularly the two center ribs, are noticeably different and more attractive. Every tread block has one long sipe, where the older design had none. The shoulder lugs are a new shape and more pleasing to the eye. Twenty-nine sizes are offered for wheels from 15” to 22”, including many of the most popular 16” to 18” sizes likely to be popular with TDR readers.

The Transforce AT2 will likely be on new Rams soon

The Transforce AT2 targets the other end of the spectrum. It’s a relatively low-void, 4-rib, all-terrain or commercial tire for those that prefer a closed outer rib, which can reduce noise and prevent wear. Many Ram owners are familiar with Firestone’s Transforce line as the OE tire for most late-model trucks, the Transforce HT or the AT. The Transforce AT is the all-terrain upgrade tread that came on my 2017 Tradesman as part of the (AD2) Snow Chief Group. The new AT2 looks very similar to the tire it replaces, but the outer ribs are a bit beefier, and there is some thin (compared to the M/T) shoulder rubber that was not present on the older design. There are 16 sizes, and I bet we will be seeing the updated AT2 on new heavy-duty Rams with the all-terrain tire option.

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:  Firestone Tire 

Superwinch EXP Series Winches

Physically large with big capability, Superwinch’s new 14, 16, 18,000# winches

At the 2016 SEMA Show Superwinch introduced their new EXP, Expedition Grade, winches in 8, 10, and 12,000# versions. At the 2017 SEMA Show they released the big dogs for the larger, heavier trucks, with new 14, 16, and 18,000# EXP Series winches. We are looking forward to their retail availability.

My last two truck builds both featured the previous generation, 12,500# Superwinch Talon.

James Langan

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

Source:  Superwinch

Cummins R2.8-Powered Proffitt’s Cruisers 79 Series Land Cruiser Pickup

Custom 79 Series Land Cruiser Pickup

Cummins’ booth at the 2017 SEMA Show was focused on their mighty mite in a crate, the fantastic R2.8 Turbo Diesel. This post is about one of the two cool rigs on display.

This Toyota was IMMACULATE! Looked NEW. Details below.

 

Custom 79 Series (HZJ79 body) Land Cruiser Pickup, by Proffitt’s Resurrection Land Cruisers.

-Chassis: 1993 FZJ80 (80 Series)

-Engine: Cummins R2.8

-Transmission: H55F 5-speed manual

-Suspension: 3-link front, 5-link rear

-Locking differentials

-Bilstein shocks

-Rigid lighting

-ARB front bumper

-Warn winch

-Vortex Sprayliner

-Maxxis RAZR MT tires

-60 gallon fuel capacity

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:

Cummins R2.8 Turbo Diesel

Proffitt’s Resurrection Land Cruisers

 

 

Hallmark Milner Truck Camper Part 1

First generation ’93 Dodge/Cummins flatbed with 1963 Bell camper. Silly looking, poor photo, but fond memories.

Heavy Loads Coming Soon

My initial Still Plays With Trucks (SPWT) column in TDR Issue 86 detailed how my Ram 2500 picked me as much as I chose it, summer of 2014. This was largely due to the ridiculously low one-at-this-price online special, plus rebates, offered by Dave Smith Motors in Kellogg, Idaho. Kind of like an old world mail order bride and a new world groom that fall deeply in-love once wed, fate.

Had I special-ordered a new truck like my prior three diesel pickups (two Rams, one Ford), I would have selected a 3500 because they are the stoutest pickups available, not that much more money, and I generally prefer extra capacity. (The 4500 and 5500 series are not pickups, despite the bodies, but Class 4–5 medium-dutys.) In 1995 I was forced to order a second generation 2500 because Chrysler temporarily eliminated the single-rear-wheel (SRW) 3500s, otherwise I’ve been a “one-ton” guy for decades.

A 3500 Ram would have rear leaf springs instead of coils. As opinionated as I am about most things automotive, I have no strong bias for either suspension. Both designs have good and bad characteristics, and I’ve praised the positives and cursed the negatives of each. Leaf springs are more proven in pickups, simple, and spring oscillation damping is less critical. Conventional wisdom is that leaf springs are better for maximum loads, but there are many variables and contrary arguments. The OE rear coils on my ’14 2500 handle maximum loads better than the soft leaf springs on my 1995 Turbo Diesel, when Dodge overcompensated for the overly-stiff first generation suspensions. Coils are not automatically softer, weaker, or incapable—the Mercedes Unimog singlehandedly squashes such claims for trucks—spring rate and the overall design is what matters. One major advantage to rear coils is their inherent resistance to axle-wrap or wheel hop. (If you need schooling on axle-wrap, read Scott Dalgleish’s Back In The Saddle column, Turbo Diesel Register Issue 88, pages 72–73.)

Coincidentally, during the first 11,000 miles, this coil-sprung 2500 has spent an impressive 42-percent of its miles loaded to GVWR. None of my prior outfits had such a high percentage of hauling miles so early, but they also saw more daily driving, a chore my current Ram does not have to endure unless I choose. (Jan 2018 update: with 42,000 miles logged, the current number is over 75% loaded to GVWR or above.) Loaded to the GVWR with what you may be thinking….

Purchased a used ’07 Four Wheel Campers Hawk to try on my 2011 Tundra.

Truck Campers

When I write camper that is exactly what I mean, a slide-in truck camper, not a travel trailer or 5th-wheel, which are often called campers but are not the same thing. Over the past few years I’ve become a fan of the smaller and nimble slide-in pop-ups. Properly outfitted they can provide luxury accommodation in some very beautiful and remote country.

Our first RV ever was a relatively primitive, 30-year-old 1963 Bell camper that we mounted atop a custom Lodi Equipment flatbed on our ’93 Dodge W350. We were cash poor in those days, and barely scraped together the “$300 firm” asking price, paying the last $20 in coins. The Bell didn’t stay around long; within a year we sold it and bought a 1978 Avion travel trailer, which we still own. We used the trailer more initially, but our trailering slowed to a trickle as RVing competed with other hobbies and responsibilities.

For twenty years my wife Beth and I had occasionally considered a slide-in pop-up, but we never bought, partially because it would add another toy to the barn, but with no extra time. Plus, over the past decade I’ve preferred private, remote, and backcountry camping to regular campgrounds. A rooftop tent, two off-road camping trailers, and eventually two Four Wheel Campers (FWC) facilitated this type of recreation. Slide-in units are not one-size-fits-all, so buying my new Ram pushed me to sell my 2012 FWC and shop for something that fits the 2500.

We liked camper travel enough in the new millennium to buy a better-fitting ’12 FWC Raven for the Tundra.

Hallmark Campers History

At the end of WWII, Hallmark owner Bill Ward’s father, Hubert Monroe Ward, started making hard-sided, pop-up trailers out of surplus aircraft aluminum in Corpus Christi, Texas. Literally a garage business in the beginning, later Hubert began making pop-up campers and moved his family to Colorado. With the explosion of the RV industry in the 1960s and 70s, the Ward family and partners owned and produced a few brands, founding Hallmark Luxury Campers in 1969. Eventually the businesses were consolidated into the one brand.

Based in Fort Lupton, Hallmark has always specialized in pop-ups designed to be comfortable in the rugged extremes of Colorado’s fabulous and famous backcountry, or worldwide. They were a high-volume producer in the past, but the pace wasn’t enjoyable. More recently the focus has been on lower volume and often slightly customized or tailored units that are built-to-order. Customization takes both time and money, but I’m selfishly happy they moved in this direction. One challenge to accommodating some special requests and features is the lack of standardization. Assembly line consistency allows for better and easier quality control, but customization requires special procedures to insure details aren’t missed.

Hallmark Campers have unique construction and quality options.

Colorado Factory Visit and Ordering

Inspecting Hallmark’s campers for the first time a few years ago at the Overland Expo West event near Flagstaff, I initially dismissed their products thinking the available amenities indicated they were not rugged outfits. I unfairly put their campers in the same class as many poorly designed and constructed RVs; I could not have been more incorrect. Researching the brand online I learned they have an enviable reputation for making stout, top-quality campers, with some unique construction features specific to their brand.

Before making such a large purchase we wanted to see more, meet the owners, and tour the factory. Fort Lupton is about 1,000 miles distant from our home in Nevada, but we had a Southwestern Colorado vacation planned for autumn 2014. After a week in the majestic San Juans, we drove north to meet the Ward family and tour their facility.

The last camper we ordered had three upholstery color options, but Hallmark offers dozens of interior fabric choices. It was invaluable to have my wife quickly and expertly narrow them to just a few, which we then discussed and agreed upon (you know who did the agreeing…). We both like earth tones and neutral colors, but admittedly I was most interested in the technical details and construction choices. The Milner model was chosen because its short length provides the most clearance in technical terrain, but Hallmark makes several models to fit different needs.

Several new campers being built during our factory visit.

Fiberglass Exoskeleton

Most RVs with fiberglass sides have a separate exterior wall that is bonded to an internal wood or aluminum frame. These panels can separate from the internal structure, which is typically caused by moisture ingress that compromises the glue, extreme heat, inappropriate adhesives, or vibration and flexing. This will never be a problem with a Hallmark; their floating exterior panels are one-piece molded fiberglass, so there is nothing to delaminate. The panels are the structural exterior and interior walls and the exoskeleton frame around which the campers are built.

Specifically, the gel-coated composite wall panels consist of a fiberglass sandwich with a structural end-grain balsa core, the same material and technique used on some yachts and military aircraft. End-grain balsa is a renewable resource that imparts remarkable strength and stiffness to the sandwich panel. The end-grain configuration of balsa provides high resistance to crushing, and it is difficult to tear. These panels handle high dynamic loads and resist fatigue.

Exoskeleton molded exterior frame and fiberglass wall offers superior durability.

One-Piece Fiberglass Roof

Water damage concerns have been the nemesis of traditionally constructed RVs for decades. To have water damage there must be a leak, which generally comes from above. To reduce the possibility of leaks, Hallmark has used a one-piece molded fiberglass-composite roof since 2010. The cap-shaped roof covers the unit with no seams or transitions to fail or maintain. Roof loads are of little concern, aside from their impact on the center-of-gravity. Walking or sitting on the roof is permitted, which is great for photography.

Hallmark offers three roof-lift systems. The standard mechanical crank-up lift is designed to raise only the roof. Both the electric and super manual systems are rated to support and raise an additional 400 pounds, should someone need to carry that much weight atop. I chose the low-geared super manual, which raises the roof in 37-seconds when using a cordless drill (the primary method) or after five minutes of hand cranking (the backup).

Setting-up or striking camp is extremely fast and simple with this lift system, better than any camping outfit I’ve used. Unbuckling the four roof latches, stepping inside, and raising the roof can be accomplished in about one minute. We love this, particularly during inclement weather, or after driving late and simply wanting to sleep.

One-piece composite roof under construction.

The roof and lift system will handle 400 lb. Insulated soft walls help maintain 70℉ in -20℉ weather.

Wood, Aluminum, or Coosa Interior Framing

Wood, Coosa composite, or aluminum internal cabinetry framing is offered depending on customer needs and preferences. Prior to spec’ing this Milner I thought surely I’d choose the newest and exotic composite material. However, Coosa saves little weight over wood, the cost is high, and wood holds a screw best and is the most repairable material should serious (collision) damage occur. With the molded fiberglass design protecting the internals, and living in dry-air Nevada, we chose wood for the interior framing. One-inch foam block insulation is standard.

Aluminum, wood, or Coosa composite interior cabinetry framing options.

An owner HIT his camper hard to cause this damage. This sight helped us chose wood for the repairability.

All Weather Comfort Soft Wall Design

Above I shared that Hallmark designs their campers to be comfortable regardless of the temperatures. Winter camping capabilities are import to me and where many RVs fail. Hallmark is proud of their cold weather performance, stating their pop-ups will hold 70-degrees inside when it’s minus 20-degrees Fahrenheit outside. Of course this includes using the furnace, but -20 is pretty cold.

The standard two-layer polyester-reinforced marine-awning-material soft walls contain a third layer of 1/4–inch closed-cell foam insulation. These thick soft walls feel substantial, and our Milner has an optional fourth-layer of Mylar reflective insulation in the walls. All our windows and vents have snap-on insulated and upholstered covers. A recent photograph on Hallmark’s website shows Canadian customers Mike and Kim Baird’s 2001 Cummins Turbo Diesel with their new 2015 K2 camper. The outfit is covered in several inches of snow in Estes Park, Colorado, and the caption says: “Any Season. Anywhere. Anytime.” I say, ’nuff said.

2015 Hallmark Milner tease… much more about this unit in part two!

Sources: 

Hallmark Campers link

Copyright James Langan/RoadTraveler. All Rights Reserved.

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

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