Cooper STT Pro: The Offroad Test

So you’ve read our initial impressions of the Cooper STT Pro, you’ve heard how they are quieter than the Goodyear MT/Rs on the road and seen how aggressive (and handsome) they look on the 4Runner. But, everyone wants to know – just how good are they off-road?

I was dying to know as well, I’d put about 1,200 miles on the tires, and the only off-road travel they had seen was a weekend trip on George Washington NF roads that were hard packed and drivable in 2wd. Our trip up to the Vermont Overland Rally changed all that.

The off-road test began immediately upon arriving at the Lillie Brook Farm during a steady Friday afternoon rain. The rain had turned the entrance to the pasture-turned-basecamp into a muddy slop that creates the vehicle equivalent of a slip-n-slide. Still at a highway-friendly 36PSI, it was time to engage 4-hi and try not to look like a dumbass driving into camp.

Fortunately, the STT Pros allowed me to maintain some dignity – while there was some slippage in the slop I could easily maintain forward progress and steer without too much yaw.

The real test came Saturday – when we aired down the STT Pros to a more trail-friendly 18 PSI and hit some of the Vermont Class 4 roads, including challenge sections from the Vermont Overland Trophy.

I’m convinced that whomever dreamed up the world’s first mud-terrain tire probably did so after wheeling in VT. The class 4 roads serve up some seriously challenging conditions. Traction is limited by the perpetually muddy trails, wet rocks, deep water crossings, and ruts.

The stakes are high with off-camber spots, tight ravines, large, loose rocks, and trees – any of which can claim a body panel (and your pride) in a heartbeat. Its an environment where you really need to be able to trust your abilities, your vehicle, and your tires.

At 18PSI on the 6,000lb 4Runner, the STT Pros bulged just enough to let you know you were working with a healthy contact patch, but not so much that you were giving up too much ground clearance – pretty much what you expect from a beefy 3-ply E-rated tire.

On the trail, the Coopers performed flawlessly. They gripped and pulled through challenging portions of the trail and offered confidence inspiring grip both on rocks and in the dirt/mud. I purposefully took obstacles extra slow, making sure to let the tires (and no momentum) drive forward progress – and the knobbies just churned over/through the terrain.

The most impressive thing about the STT Pros was their lateral grip. A heavy truck in off-camber situations, inches from trees and embankments is an uncomfortable thing. In these situations, the Coopers help their lines, and I was even able to give meaningful steering input without losing my line.