Since this thread has been resurrected from the dead, I'll add an update on my experience with Cooper ST/Maxx tires purchased in March 2014:
Size: LT265/75R16-E
Date purchased: 3/25/14
Miles to date: 22,407
Tread remaining: 45%
Punctures/repairs: none
Estimated tread life to 4/32" tread depth: 35,000 miles
I like these tires and will likely purchase another set in the LT255/85R16 size in March 2018 (when Cooper typically offers spring discounts). They have stood up to two trips to goneMOAB, frequent trips to the Sierra Nevada mountains and the deserts of California and Nevada, also numerous long distance road trips on the Interstates. As with all open void tires, the noise level has increased as the tires have worn - the key to keeping this to a minimum is to rotate and re-balance consistently, which I do every 4,000-4,500 miles. I have found that the optimum tire pressure for my particular tires on my particular truck is 35 psi around town and 38 psi for long runs on the Interstate. I typically air down to 18 psi off road.
I do not get much snow in my area so I cannot evaluate snow performance, however my best guess for a snow rating would be above average for this type of tire based upon performance in the rain, which is very good. I have no complaints about handling on dry pavement, gravel or other "semi-improved" surfaces. Performance has been excellent offroad. Traction off road is as good or better than any other AT type tire I have used and many MT tires. They have balanced well and highway ride has been smooth and straight.
Tire wear has been very good for aggressive AT tires which are frequently used off road. Based upon tread wear so far, I expect to get 35,000 miles from these tires before they wear to 4/32" tread depth, which is when I typically replace tires rather than take them down to the legal limit of 2/32". That is as good or better than other AT and MT tires I have used through the years.
In my opinion, the Cooper ST/Maxx is one of the top tire choices for a Gen II Xterra that is used on the highway and frequently off road.