The Cooper Discoverer STT is the latest version of the company's Discoverer tire lineup. In addition to a very functional and visually appealing tread design that includes deep buttress lugs that extend down the sidewall, the new Discoverer STT uses the company's unique Armor-Tek3 carcass construction. Armor-Tek3 employs use of two radial polyester body plies and one angled polyester body ply. In all, three plies encompass the tread area to achieve excellent resistance to impact breaks and bruising. The computer-designed, nondirectional STT tread is the best off-road design yet of the Discoverer tire line. STT stands for "Super Traction Tire," and Cooper isn't far off with this designation.
The Cooper Discoverer STT performed exceptionally well in hard-packed and soft dirt terrains and also shined on the rocks. Initial rockcrawling attempts on obstacles while at a higher psi were acceptable but improved greatly as we lowered the tire pressure. The Cooper Discoverer STT seems to have a natural ability to conform to rocks and even more so once the ideal off-road pressure is determined. We felt comfortable dropping to 10-12 psi using our nonbeadlocked Pro Comp wheels and would perhaps go even lower should the terrain call for it (and at a time when we are better prepared to slip the tire off the wheel, should that occur). Nonetheless, the 10-12 psi range appeared to work well for this tire while in the dirt and rocks; the loose dirt, almost sandy, sections were also easily conquered with the Discoverer STT tires in this psi range.
Another benefit of these tires are the beefy, scalloped shoulder lugs that extend from the tread down the sidewall. These tread blocks are great aids in a variety of conditions but were especially helpful in obtaining and maintaining traction on rocks where it was necessary to ride the sidewall to clear the obstacle. The side lugs also offer increased obstacle coverage when aired down, which not only helps save the sidewall area from undue wear or damage but also permits continued traction across the entire contact patch of the tire.
The STT's street manners were also up to par for an aggressive-tread tire of this type. On-road handling was easily manageable and seemingly unaffected by the larger tire size or tread. Steering response also remained fairly nimble and road noise was minimal compared to that of similar tires we've tested.
In all, the Cooper Discoverer STT proved itself a very capable and user-friendly tire. It has the attitude of a mud-terrain tread but still responds with authority to highway and other on-road driving situations. Aside from its impressive performance abilities, we also really liked the design and appearance of the Discoverer STT and received similar impressions from all others we encountered who noticed the new treads.