Cooper Discoverer A/T3 And S/T Maxx Tire Review

Discoverer S/T MAXX
Overview: The S/T MAXX features Cooper’s three-ply “Armor-Tek3” carcass construction, which means it has two normal radial plies run at 90 degrees from the bead and a third Armor-Tek3 protective ply at a unique angle to the two normal radial plies. Cooper says this arrangement adds strength and durability to the tire. It has a proprietary blended natural rubber and silica-based tread compound that offers great wet traction and excellent cut and chip resistance. It has a hybrid 4-5 rib tread design that helps create a quiet ride and positive grip, and it 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.

Behind the wheel: We began our test of the S/T MAXX on the 100x16-foot Rock Crawl/Sidewall Durability Course. This limestone boulder course is designed to demonstrate low-speed rock traction and resistance to tire bruising, tread cutting/chipping and sidewall puncture. The tires were set at 15 psi and mounted on a Jeep Cherokee XJ. One of the first things we noticed was that the tire exhibited a noteworthy ability to conform to the rocks and pull the XJ along. And thanks to the aggressive outer edge of the tire, we were able to plant the shoulder on boulders numerous times without slipping off. We also appreciated the rugged construction, which decreased the likelihood of sidewall damage during these maneuvers. Next up was the Hill Climb area. Here, we drove up two 30-foot-long climbs that have an angle of 30 degrees with 1/10 inch of water flowing over the surface. These areas are designed to test the tire’s compound and tread pattern effectiveness. The first was a smooth concrete surface, and we expected that the more aggressive lug design would contribute to tire slippage. Conversely, the tire stuck to the wet concrete like glue and carried us to the top numerous times (even backwards) with no wheelspin. The other climb was a brushed concrete surface with embedded rock. This was a very challenging surface, but the tire did well as the compound and tread combined to latch onto the mix of surfaces and pull us to the top. Finally, we took the tire out to the 1.5-mile-long Trail Ride Course, which contained a variety of conditions including mud and water. Once again, we were impressed by the tire’s ability in all of those settings. Following an afternoon of crawling on a number of obstacles including sharp rocks, the S/T MAXX didn’t show any signs of “chunking” and the lugs were intact.

Bottom line: If you’re looking for a tire that can handle rougher terrain, but you also want a tire that’s designed to be quiet on-road with excellent wet weather traction, the S/T MAXX may be what you’re looking for. This tire will eventually replace the Discoverer S/T-C and selected sizes of the S/T. It is currently available in eight light truck sizes with more coming in early 2012. fw

»The Details
Tire: Cooper Discoverer S/T MAXX
Size: LT265/70R17
Type: Radial
Load range: E
Max load (lb): 3,195 (single), 2,910 (dual)
Sidewall construction: 3-ply poly
Tread construction: 1-ply nylon, 2-ply steel, 2-ply poly
Approved rim width (in): 7-8.5
Tread depth (in): 18.5⁄32
Tread width (in): 8.7
Section width (in): 10.7
Overall diameter (in): 31.8
Static loaded radius (in): N/A
Revolutions per mile: 652
Weight (lb): 55