We Hit The Dirt (and Pavement) With These New Tires
A couple of years ago we had the chance to test the then-new Cooper Discoverer S/T MAXX tire on a closed course at the company’s Tire & Vehicle Test Center in Pearsall, Texas. We spent several hours driving S/T MAXX-equipped Jeeps on a variety of off-road terrain and obstacles. We left with a positive impression of the tire, and since then we’ve had a longing to spend some quality time with the tire in the real world. Would it live up to the favorable impression we had during our brief experience?
Well, that time finally arrived and we recently helped the UPS guy unload a set of LT285/70R17 (33x11.50R17) S/T MAXX tires that we installed on our ’05 Dodge Power Wagon. To review, the S/T MAXX features Cooper’s three-ply “Armor-Tek3” carcass construction that features two polyester plies that run diagonally from bead to bead across the tread. The third polyester ply also runs from bead to bead, but is at a 45-degree angle compared to the other plies. Cooper says that the 45-degree angle of the third ply creates a weave pattern that aids in puncture resistance in rough applications. Further, with all three plies running from bead to bead, the strength benefits are achieved in both the sidewall and tread area of the tire. The tire’s tread construction consists of one nylon ply, two steel plies, and three polyester plies. The tire also has a proprietary blended natural rubber and silica-based tread compound that is touted as having great wet traction and excellent cut and chip resistance. Cooper says the tread design is a hybrid (meaning part all-terrain and part mud-terrain) 4-5 rib tread design that is intended to create a quiet ride and good grip. The tread also features stone ejector ribs, dual-draft walls, and non-parallel groove walls that combine to help resist stone drilling and retention. The outside edge of the tire features an “enhanced buttress” design that serves several purposes. It provides additional traction, helps resist abrasion, and helps prevent lug tearing. The tire also features a rut guard rib and rim protector.
During testing, we covered a considerable number of miles both on- and off-road. On one road trip, we left our northern Illinois Four Wheeler Midwest Bureau and traveled via interstate to northern Wisconsin and the upper peninsula of Michigan, where we spent quite a bit of time exploring unpaved roads and trails near Lake Superior.
When we tested the tire in Texas, we didn’t have the opportunity to use it at highway speeds on paved roads. Typical of most 4x4s, this is where our truck spends well over half of its time, so performance in this area is critically important and we were curious as to how the tire would do. We have to admit that we thought the tire would be noisy, and we’re not a fan of that on daily-driven rigs. We were pleased to find that the design of the tire makes it remarkably quiet on the highway. Yes, the tire makes more noise than most all-terrain tires, but no, it’s not overly loud. The tire’s natural rubber/silica tread compound helped to create excellent wet weather traction. Driving in the rain was a no-drama event, both in the traction and handling departments. All of the S/T MAXX tires are load range E-rated and the ability to run higher inflation pressures and carry heavier loads was welcome on our truck that is often used to tow and haul. The S/T MAXX tires served up a slightly stiffer ride than the load range D tires they replaced, but it wasn’t out of line.
When you read the S/T MAXX information provided by Cooper it becomes clear that the tire was designed to excel in off-road situations. The majority of the information in the company literature deals with the tires ruggedness and off-road attributes. We like that. We spent a fair amount of time off-road with the tire and we documented some of the terrain we encountered, and our thoughts, in the accompanying photos.
In the end, our positive impression of the tire continues. We think the S/T MAXX is a tire that is perfect for a 4x4 that spends more time than average off the paved road. We think that the tire is a great choice for a 4x4 that’s used for towing, hauling, and off-road work. It’ll pick up where an all-terrain tire leaves off in the rough stuff, while still exhibiting very good on-road manners.
Tire: Cooper Discoverer S/T MAXX
Load range: E
Max load (lb): 3,195 (SRW), 2,910 (DRW)
Sidewall construction: Three-ply polyester
Tread construction: One-ply nylon, two-ply steel, three-ply polyester
Approved rim width (in): 7.5-9.0
Tread depth (in): 18.5⁄32
Tread width (in): 9.3
Section width (in): 11.5
Overall diameter (in): 33
Maximum psi: 80
Weight (lb): 60
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