One in five light truck tires sold in the US is made by Cooper Tire.
So it’s no surprise that in the world of off-roading, the Cooper Tire Discoverer STT is a popular choice. Representing the most hardcore off-road tire in the Discoverer family, the STT is built for extreme traction, designed to handle anything you can throw at it.
But the Discoverer STT has been around for quite a while now and it’s time for a change. As of June 1st, Cooper Tire is selling the next generation in the company’s maximum off-road tire; the Discoverer STT Pro.
The new Discoverer incorporates everything Cooper Tire has learned about off-road tire design. Using a hard to puncture armour-tek3 sidewall construction the STT Pro is a 3-ply tire, which offers a 50 percent protection increase over a regular 2-ply tire. The new Discoverer will even protect your fancy off-road wheels thanks to a built in wheel protector rib.
One of the key design elements to the STT Pro is the 3-2 inner ribs. The 3-2 refers to tread pattern that alternates between three ribs and two ribs. This helps with vehicle stability, mud traction and off-road ability.
Dry and Wet Performance
To ensure the Discoverer STT Pro doesn’t get stuck in the mud, the tire comes with mud scoops and mud dimples. The former digs into the mud to gain traction while the latter ejects it out of the tire to keep the tread clean. There are also rubber side cleats to further dig in and gain traction on soft, loose surfaces.
Unlike a lot of hardcore off-road tires, the Discoverer features a silica rich compound and various depth sipes. This helps the tire gain traction on smooth, wet surfaces as well as snowy conditions.
But a lot of off-roading is done on dry, rocky trails and the STT Pro is designed to handle that as well. With angled groove walls, the tread pattern is designed to keep stones from getting caught in it. As well, the new Discoverer continues to incorporate cut and chip compound additives that help prevent punctures over jagged, hard surfaces.
Putting it to the Muddy Test
So the Discoverer STT Pro has all the goods to handle off-roading, but does it deliver on that promised performance? Four years ago I had the chance to visit Cooper Tire’s San Antonio test facility that features a full-fledge off-road course complete with a gooey mud-pit. At that time, I drove the Discoverer STT mounted to Jeep Cherokee XJs and came away impressed.
This year I was back to drive the new STT Pro on the same course. First up was a man-made concrete wall set at a 30 degree angle. Split into three sections, one features a scuffed surface, another embedded rocks and the third a polished surface. The Polished ramp is designed to simulate a boat ramp, complete with wet surface.
The STT Pro tires were installed on modern Jeep Wrangler Unlimited JKs with a mild lift kit. To start, we were asked to drive halfway up the polished ramp and stop. Then, hit the gas as hard as we want to climb the rest of the way up. The Jeep took off like it was on a dry flat parking lot with zero wheelspin. When I did this same test with the old STT tire, it succeeded too, but with some tire spin. On the embedded rock wall the STT Pro performed drama free as well.
Next it was off to the mud pits. A giant field with industrial sprinklers soaking a silt dirt surface creates some impressively deep mud. When we did this challenge four years ago with the STT, the Jeeps had no issues running amuck in the messy field. But this year, we were asked to put the Jeeps in two-wheel drive instead of four-wheel drive like we did four years ago.
SEE ALSO: Cooper Tire Discoverer SRX Review
Although progress was slow, the STT Pro tires refused to get stuck. Even when they began to bog down and it felt like this was when the tires would stop forward progress, they didn’t. By working the throttle, the tires would continue to claw away at the mud and continue moving the Jeep across the field. In four-wheel drive, the tires may have well been on a grass field as the mud was no match for the STT Pro.
As a final test, we visited a small creek bed with a large, steep exit consisting of several random rocks. Four years ago this proved to be the nemesis for many unfamiliar with off-roading. Not everyone could get the Jeep to exit the pit, despite the STT’s abilities. This year though, it wasn’t an issue at all. Everyone just drove out of the creek bed like it wasn’t even an obstacle.
The Verdict: Cooper Tire Discoverer STT Pro Tire Review
The new Discoverer STT Pro will be available in 41 sizes for wheels measuring 15- to 22-inches in diameter. Available in both Q and R speed ratings, those who like their tires big will be happy to know the STT Pro can be had in the monstrous 325/50R22 configuration.
Although my time with the STT Pro was brief, it’s a definite improvement over the regular Discoverer STT. But, some of this increased performance may have to do with the STT Pro being equipped to modern JK Wranglers compared to the old STT tire I tested years ago on older XJ Cherokees. What is for certain though, if mounted on the right off-roader, the Discoverer STT Pro is virtually unstoppable.
- The STT Pro is available in 41 sizes.
- The STT Pro comes in wheel diameter sizes ranging from 15- to 22-inches.
- Built with 3-ply tire technology
- Available in Q and R speed ratings