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Cooper Discoverer S/T Maxx: Just Works

Posted in How To: Wheels Tires on March 1, 2012
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Most Jeepers fall into one of two categories: a rock hound or a mud freak. But every once in a while we run into one of those Jeepers who likes Jeeping so much, it doesn’t matter what kind of terrain it is. The Cooper Discoverer S/T Maxx is the newest member of Cooper’s lineup and it is a lot like that. Its mild-mannered looks are somewhat deceiving as we didn’t find any terrain it didn’t like. Upon first glance we were sure we’d end up with banana peels in the mud, but that wasn’t the case. Sure, it did better in some than others, but what tire doesn’t?

We mounted our 285/75R16 on a set of Ballistic Off Road Outlaw wheels under Trasborg’s ’91 Comanche and started terrorizing the highways and byways. Ok, we didn’t actually terrorize anything. Two tires took 5 ounces of weight but the other three took under 3 ounces. Once set to 28 psi (front) and 27 psi (rear) we found the tires to have a low hum at slower speeds, but by the time we are up to freeway speeds, we don’t even know they are there. In the twisty canyon roads we often drive, they didn’t exhibit any push despite having a spool in the back on dry roads. Surprisingly, on wet roads, the ass end of the truck was less likely to come around with throttle than all terrains we had on it before even though the S/T Maxx tires have less overall siping. We did notice a slight loss of mileage over the mild-mannered tires we had on the Jeep before, but for the increase in off-road performance we are willing to accept it.

Our Load Range E were all that was available in this size as of press time and feature Cooper’s Armor-Tec3 technology with a 7-ply tread (2-nylon; 2-steel; 3-polyester) and 3-ply sidewall (3-polyester). It is way too much tire for the truck, and while we did get a decent contact patch at 10 psi, we think they would have worked better in heavy rocks at a lower pressure. However, we were leery of losing a bead with no beadlocks on the truck.

That said, at 10 psi these tires do quite well in the mud. The high-void stepped-shoulder lugs feature mud ribs do a good job at breaking suction so the shoulders clear enough mud to keep forward momentum, even at lower wheelspeeds. The more closely packed center lugs, unsurprisingly, take a bit more wheelspeed to clear out. In some thicker, clay-based mud, the shoulders take a bit more wheelspeed to clear, but the center lugs didn’t clear until we’d almost hit the rev-limiter. That said, forward momentum was still possible until we got much below axle-depth.

In the sand, those center lugs seem to stop the tire from trying to dig to China while the outer lugs just move the silica out of the way. By no means are these paddle tires, but forward movement was easy to attain from a full stop and maintaining forward movement wasn’t hard either.

In high-speed hard-pack terrain, we drifted through corners trying to get the tires to chunk. But even in rock-infested trails we could only create small chunks by spinning the tires, and these were nothing that affected the function of the tire. In low-speed hard-pack, the tires had no problem pulling the Comanche up climbs in low range and First gear.

In the rocks, we simply didn’t worry about damaging the carcass. Between the extra plies in the tread and the 3-ply sidewall, we just played point-and-shoot. We had no problems in anything from smooth granite to small, round boulders. With no armor under or around the MJ, we had to be a bit selective in what we crawled over, so we didn’t tackle any Volkswagen-sized rocks. However, at 10 psi with our relatively light Comanche, the tires didn’t envelope the edges of sharper rocks as much as we’d have liked them to. Even though the load range is way more than what we need, we are going to keep them in the stable for quite a while. The Cooper Discoverer S/T Maxx might not excel at any one terrain, but there is no terrain we found it to be lacking in, either.

• Good in wet on-road
• Bulletproof on a Jeep
• Balanced with minimal weight

• Low growl at low speeds
• Load Range E only in this size
• Loss of mileage over all-terrain

Put ’em on
• Daily driver/weekend warrior
• Fullsize Jeep
• Any Jeep you want to be able to drive home


Ballistic Offroad
City, AK
Cooper Tire
Findlay, OH 45840

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