With the advances in tire technology, the lines separating different tire types are now razor thin. We have all-terrain tires with incredible off-road performance and dedicated mudders that can still be run on the road without too much compromise.
The latter situation applies to the Cooper STT Pros. This is the most aggressive tire offered by the brand, and while it may technically be a mud-terrain tire, it has many of the characteristics of a less aggressive all-terrain tire, promising great grip in the mud and decent on-road dynamics.
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It mostly delivers on those promises, but let’s just go ahead and get the biggest downfall out of the way: these tires are not quiet. You can hear a pronounced hum while rolling down the highway.
That is easily the biggest compromise you’ll deal with by putting STT Pros on, but compared to many dedicated mud tires, these Coopers are actually a little quieter. Bottom line: It’s a bearable amount of noise in our opinion, and worth it for the performance of these tires.
The STT Pros begin with a three-ply carcass that uses a proprietary process called Armor-Tek3 that overlays the third ply over top the other two at a small angle, which is meant to take away any rubbery weak points in the tire.
When it comes to features, it’s pretty clear that the STT Pro is mostly focused on ripping through a bog, but some time was spent here to help keep these tires civilized on-road, namely the alternating tread ribs that go from three to two and repeat. This allows the tire to have big mud-grabbing spacing between half of the treads, while every other set of ribs is spaced more like an all-terrain tire.
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This helps to reduce road noise down from what you get with a straight mudding tire and it also allows the STT Pro to handle well on the pavement. There is also a flex groove at the edge of the treads, allowing them to bend and absorb the impact of broken or rough pavement.
Now, back to the muddy stuff. Big side biters are seen on the shoulder and coming down the sidewall of the tire, helping to advance traction and grip. These also help when you need to squeeze the side of that tire into a rock or rut to help gain traction.
And finally, thought and attention was paid to mud grip thanks to asymmetrical scallops, meant to channel the mud into the mud scoops, which bite into the soft earth and pull the truck forward.
All sounds great on paper, but how does it work in practice?
In Search of Mud
We went on a quest to find the mud with our STT Pros to put them through a proper test, and the long narrow path into the mud pit saw us tackling dry rocks and sloppy mud trails with big, unavoidable ruts.
Even with the skid plate just dragging when the ruts were at their deepest, it couldn’t stop these Coopers from finding traction and pushing ahead. On the rocks, they climbed easily and the brakes felt strong on downhill sections thanks to the tires grabbing the earth.
Eventually, we found the mud hole at the end of the trail and crashed into it with reckless abandon. Thing is, that wasn’t necessary to make it through. Each subsequent pass had me going slower and slower until I built up the courage to stop with the wheels while half submerged in water, at the bottom of which was thick, sticky mud.
The slow-speed traction that these tires offer in these conditions is superb, with our truck pulling out of the mud like it was taking off when the lights turns green in traffic.
The promises made about the road performance of the tire may not be entirely true, but get the STT Pro into the mud and it delivers everything promised and then some.
Back to the Road
Pulling back out onto the road is when you recognize the strong suit of this tire: dedicated mud performance that doesn’t ruin the drive of your vehicle.
These tires aren’t floppy or soft going through corners, only making our Ram 1500 feel slightly more cumbersome than when the stock all-terrain tires are mounted.
Overall ride comfort wasn’t affected the best that we could tell, and even the difference in handling is slight.
Opting for something as aggressive as these STT Pros doesn’t come too cheaply. For the smallest set of these Coopers, you’re looking at spending about $250 each, while at the top end the STT Pro can run as much as about $450 each.
The Verdict: Cooper Discoverer STT Pro Tire Review
Cooper is once again trying to split two segments in the tire world, and the brand appears to have succeeded. You’ll have to live with a little more road noise, but what you get in return is an excellent off-road tire that feels just as at home on the pavement as it does in the mud.