I installed a set of the Cooper ST tires in 255/85-16 in August of 2010 on my 2005 Jeep Rubicon Unlimited. I have waited to post a review of them until I had gotten most of the life out of them that I could. I am just about at that point and will share my thoughts as succinctly as I can. The tires were mounted on stock Moab wheels, and the Jeep is on its original suspension.
First impression was . . . not good. I had them mounted and balanced at the local tire shop where I bought them on a Friday. They rode fine, were reasonably quiet, and I was happy. The next day I went wheeling/rock crawling at our usual haunt (Rausch Creek ORP). After getting home I discovered a split in the sidewall. I was rather dismayed, and the following monday I called the local tire shop and told them what I found. I suspected a defective tire, as there was no rock rash or sign of impact near the split. I had 28 psi in the tires for the trip (I run 32 on the pavement). They asked me to bring it in to see what was up. They looked at it, and declared it just a superficial/cosmetic cut in the outer side wall casing, and I could drive on it as is without issue. 3 days later, the tire failed (deflated) completely, luckily overnight as it sat in my driveway. I put on the spare, took the 1 week old tire to the shop, and was told I was out of luck. Cooper would do nothing, and they would do nothing. Pissed off, but with 3 other nearly brand new tires on the truck, I bought another single tire and left the shop - never to return.
Since then I have taken the truck wheeling numerous times, without further incident. The tires have been wearing well, and now have about 35k miles on them. I typically get 38-42k/set of tires on my daily driven rig. Tread depth on the coopers is down to the last 20% or so, but they worked GREAT last week back at the Northeast property at RC. In fact, I ran outer limits with them (for those that know the trail-it is a blue/black and was part of the KOH RCQ race course), and I was truly impressed with their traction and performance in the rocks as well as some mucky stuff. I was starting to consider getting another set for my truck. Then a few days after the last trip to RC I noticed the RF tire was low. I reinflated it, and found another cut sidewall. The tire is likely done/unrepairable. So, I am no longer going to consider these tires for my next replacement cycle.
In a nutshell - these are good tires in terms of overall performance, with the SIGNIFICANT exception of the vulnerable sidewalls. Both cuts/failures were in an UNLOADED rig. If you stay off the rocks, and mostly run gravel and easy trails, you may never have an issue with the sidewalls. Wet traction is overall excellent, however now that the depth is lower I notice less grip (not hydroplane) on wet pavement. Not as bad as the OEM Goodyear MT/Rs, but not as good as my previous tires (Maxxis BigHorn). Snow performance was average. The Maxxis tires were better in the snow, IMO.
My next tire will be the Toyo Open Country in 255/85-16, which has an E/10 ply rating and armored sidewalls. They are a bit heavier than the Coopers, but much stronger.
That's my take on these tires.
