At Cooper's Tire & Vehicle Test Center near Pearsall, we were turned loose in four-door Wranglers shod with STT Pros, having fun in the mud — up to almost the axles at points — and scaling seemingly impossible grades and surfaces. Just three weeks later as the storms' devastation made national news, we were given a brutal reminder that traction can mean life or death.
The STT Pro is designed to fling off mud, small stones and other debris. The off-road rubber is available in 41 light truck and flotation fitments in 15-, 16-, 17-, 18-, 20- and 22-inch rim sizes ranging from 30x9.50R15LT to 37x13.50R22LT and LT325/50R22. The new line covers C, D and E load ranges.
Cooper, led by product segment manager Mike Stoltz, briefed reporters on the STT Pro's finer points. The STT Pro has two conventional radial plies and a third “Armor-Tek3” ply applied at an 8-degree angle for increased sidewall puncture resistance.
Its high-void tread pattern is designed to conquer mud, sand, rocks and loose soil. Asymmetrical scallops funnel mud into “scoops” so the gunk can be evacuated. Tiny “mud release dimples” help prevent the mud from sticking.
The silica-enhanced compound is designed to resist cuts and chips and gets some help from a raised rubber rim flange protector built into the lower sidewall area.
To deal with the inevitable on-highway noise inherent in most off-road tires, Cooper designed the STT Pro with an alternating pattern on the inner tread that not only helps reduce noise, it improves stability and handling and promotes more even wear.