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

Rt3 Tire
Ken Brubaker
| Senior Editor, Four Wheeler
Posted July 1, 2011

Two New Members Join The Discoverer Family of Tires

Recently, we were invited to the Cooper Tire & Vehicle Test Center (CTVTC) in Pearsall, Texas, to see the all-new Discoverer A/T3 and S/T MAXX tires.

The CTVTC was built in 1999 at a cost of over $13 million and it encompasses 1,000 acres. It is home to a number of testing areas, including many that apply to us off-highway fans. The Off Road Course includes just about every type of obstacle one could encounter off-highway, including a rock garden, rock hillclimb, mud, silt, and gravel. We tested the new A/T3 in the mud as well as on the 14-acre Wet Vehicle Dynamics Assessment Pad (commonly known as a skidpad). We were able to test the S/T MAXX on almost the entire Off Road Course in addition to a wet concrete hillclimb.

The all-terrain A/T3 and the mud and snow-rated S/T MAXX are the newest products to be rolled out by Cooper in the Discoverer line, which has a lengthy history of over 30 years. During the design phase of the tires, Cooper set out to identify what the average buyer for each type tire wants and then they integrated these features into the tires. Here’s what they came up with.

Discoverer A/T3
Overview: The A/T3 features a five-rib design, and the tread elements are coupled together to provide stability and confident on-road handling. The center rib is divided, and Cooper says that this improves off-highway traction without sacrificing on-road performance. The tire includes a couple of features designed to provide reliable soft-surface traction. One is the aggressive shoulder and the other is the wide “Chevron”-style circumferential grooves. Those grooves also help the tire clean itself when off-highway. The tire’s thin-gauge, zig-zag-shaped siping helps to accomplish a few things, including the reduction of stone retention, and it improves the stability of the tread blocks. And speaking of stone retention, the tire was designed with lateral groove protectors that have serrated steps to reduce the chance of stone retention and stone drilling. Another noteworthy feature of the tire is that the tread compound is a silica-based formula, which is a key to the tires wet weather performance.

Behind the wheel: The silica-based tread formula demonstrated its benefits on the Wet Vehicle Dynamics Assessment Pad, which contained a 2/3-mile, cone-lined course designed by Cooper. The course contained gradual and sharp turns, simulated lane changes, and areas to test acceleration and deceleration. We drove three identical Chevy Silverado pickup trucks, two fitted with competitors’ tires and the other with the Discoverer A/T3. When driven back-to-back, it was clear that the A/T3 had the upper hand in the wet stuff. The silica-based tread formula gave the tires a traction advantage we could feel, and the siping and design of the tread blocks were confidence-inspiring as we pushed the truck hard through the wet course. The improvement was illustrated by the fact that we averaged faster lap times using the A/T3 than the other two sets of tires. We also had the opportunity to immerse the A/T3 in Cooper’s Mud Traction Area, which is a continuously-watered, 500x150-foot mud hole. We didn’t expect much out of the A/T3 here—after all, it’s an all-terrain tire, not a mud-terrain. Imagine our surprise when the A/T3 showed itself to be amazingly capable in the goo. We drove an A/T3-equipped Jeep Wrangler TJ on the course at length and were impressed by the tire’s ability to clean itself and get a fresh bite with each rotation.

Bottom Line: If you need an all-terrain that really does excel in all terrains, the A/T3 is worth a look. There are many neat ideas integrated into this tire. The A/T3 is slated to replace the Discoverer AT/R, and by the time you read this it will be available in 31 light truck sizes and 30 P-metric sizes with a 55,000-mile warranty.

»The Details
Tire: Cooper Discoverer A/T3
Size: LT265/70R17
Type: Radial
Load range: E
Max load (lb): 3,195 (single), 2,910 (dual)
Sidewall construction: 2-ply poly
Tread construction: 1-ply nylon, 2-ply steel, 2-ply poly
Approved rim width: 7.0-8.5
Tread depth (in): 16.5⁄32
Tread width (in): 10.9
Section width (in): 8.5
Overall diameter (in): 31.6
Static loaded radius (in): N/A
Revolutions per mile: 659
Weight (lb): 50


Cooper Tire
Findlay, OH 45840
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