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’s new Deegan 38, 5-rib all-terrain design.

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

Ridge Grappler from Nitto Tire

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 

Copyright James Langan/RoadTraveler. All Rights Reserved.

 

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.

© James Langan/RoadTraveler.net

Cooper S/T MAXX mounted

Today I’ll be working on continuing this series. Until the words are ready here is a little taste.

Cooper S/T MAXX LT275/70R18E

RoadTraveler.net – Rollin’ Forward

Copyright © 2012 James Langan

Cooper S/T MAXX LT275/70R18E Preview (Traction Tire Part 2)

The Cooper S/T MAXX 

After deciding the LT275/70R18 was my perfect 33-inch tire for an 18-inch wheel, and seeing there is a nice selection of tires in this size, a tread had to be chosen. This was relatively easy as I’m familiar with most of the popular light-truck traction tires. I’m a fan of Cooper Tires and their subsidiaries, and the new S/T MAXX design was already on my to try list, offering the type of any-terrain tire I prefer—not too biased toward on or off-highway. Cooper calls this a 50/50 tire (on/off pavement) and I’d say they are very close to hitting that mark.

LT275/70R18E Cooper S/T MAXX

After some online shopping, my local Discount Tire matched a price from TireCrawler, a mere $242 each delivered. (This was a few months ago; tire prices change, usually increasing.) Discount ordered the tires and a few days later I hauled my 18-inch wheels to their shop for mounting and balancing. Cooper says the LT275/70R18E MAXXs are 33.35 x 11.2 inches and my scale said they weigh 60.5-pounds each. Combined with the relatively heavy, 30-pound, 18-inch cast aluminum SR5 Tundra rims, each tire/wheel combo weighed 91-pounds!

Stout Construction

Once you get your hands on one, there will be no doubt the S/T MAXX is a super stout tire. The scale tells part of the story, though not all load-range E or 3-ply sidewall tires are created equal (see Wheels, Tires, and Sidewalls). Grab an unmounted ArmorTek3® sidewall and give it a good jerk back and forth, they’re stiff, similar the Toyo MT, and more substantial than the 3-ply sidewalls on the very common BFG All-Terrain. The MAXX sidewalls are much stiffer than the older and lighter-duty Cooper S/T, which offers flexible sidewalls and very little sidewall tread. Similar name, and I like both treads depending on the intended application, but they are very different tires. Try not to confuse the S/T MAXX with the S/T, or the Cooper STT… maybe Cooper needs some new letters?

The S/T MAXX has beefy sidewall lugs/tread.

The S/T MAXX is an impressive looking tire. The sidewall lugs are attractive and thick, more impressive in person than in the photos I’d seen, and possibly the most aggressive sidewalls I’ve seen on a tire in this class (not a mud-terrain). The tread is a hybrid 4–5 rib design with a bit less void than the older 4-rib S/T, the center circumferential groove is noticeably missing. There is a moderate amount of siping and the cut & chip resistant compound is studdable. Cooper describes the MAXX as a “commercial grade traction tire”, an accurate description.

S/T MAXX 4-5 rib hybrid tread design.

Mount & Balance 

Mounting a 275/70R18 S/T MAXX on Tundra 18 inch SR5 aluminum wheel.

Mounting the first tire and giving it a spin on the balancer showed it wanted 3.25-oz. inside and 4.75-oz. outside for a dynamic balance. Eight ounces is not much weight for a 91-pound spinning mass, but I generally like to add less weight to my wheels when possible.

While dynamic balancing is the technically the best as it balances in two planes, I’ve had many positive experiences using the single plane static balance method for heavy RV tires (an old term). Static spin balancing counters vertical imbalance (hop) of a tire & wheel, and I don’t run very wide tires where dynamic balancing can be more important. Generally, I see how the first couple tires in a set balance and if they can be dynamically balanced with moderate weight, that’s what we do. If they are going to ask for substantial weight using the dynamic method, I choose static.

Modern balancing machines are very good.

Sometimes this difference can be very dramatic. A few months ago a heavy, high-quality tire wanted about 9 ounces for a dynamic balance, but only 1.5 ounces for a static balance. Guess which one I chose? The S/T MAXXs were single pane balanced and the road force (RF) was also measured—which was very low—another indication of quality. For more thoughts on tire balancing you can read Static Balance Details.

Static Balance Numbers

#1) 4.75-oz. RF .002″.

After seeing this low road force number the kid doing the balancing commented “Wow, that’s like a Michelin.”

#2) 4.25-oz. RF .008″

#3) 5.50-oz. RF .007″

#4) 1.50-oz. RF .009″

Cooper Tires’ website lists the tread depth for every S/T MAXX currently made as 18.5/32″, which it probably is. But it would be pretty easy to call this 19/32″ as measuring down to one-sixty-fourth can be a challenge. The original tread depth is important, more is better for most truck tires, though the long-term wear rate is also important. Combine deep tread with a low rate of wear and you have a long-lasting tire.

LT275/70R18E COOPER S/T MAXX tread depth.

Because my original 17-inch Tundra TRD wheels use tapered lug nuts, which are uncommon for modern Toyota trucks, I needed new shank-style nuts for the 18-inch wheels. Searching online I found a source for the Gorilla brand lug nuts and locks, a complete set was delivered for about $110. I’ve been using an impact-gun on Gorilla wheel locks on my 4Runner for years, and they have held up to my intense use. I wish they would fit on the OE 17-inch TRD Tundra wheels.

Shank style Gorilla locking lug nuts needed for SR5 wheels.

Driving Impressions

To be continued…

Copyright © 2012 James Langan