Charley3, you're a piece of work. I mean that as a compliment.
I was, twice, very satisfied with the Pirelli Scorpion AT that I used to use on my XJ and again on my WJ. Sadly, no longer offered.
Now, thanks to you, I'm looking at the Cooper AT/3 and thinking, they look vaguely familiar. Their tread pattern reminds me of the Scorps. I realize tread pattern isn't the only variable conducive to a tire's abilities/attributes, but I couldn't shake the coincidences in those respects.
I haven't read every page here, but has the long term use of the AT/3 been discussed?
Is there a time, mileage-wise, when the performance just falls off?
As far as I know, no one has owned them long enough to judge long term. They are relatively new.
All I can say is that Cooper talks about a few design features (including deep sipes) that allegedly keep the tire performing well for its life. Also, it has a 55,000 miles warranty, which is better than most brands of AT.
By contrast, BFG AT sipes are very deep IME, and BFG AT has a dual tread compound with the half of tread closest to carcass being harder rubber (to stabilize tread blocks and to increase wear) and the half of tread farther from carcass being soft for traction. This gives both good traction and handling when tire has less than 25K to 30K miles, but after that the soft grippy rubber is worn off, and only hard slick rubber is left. This is why BFG AT perform so good when low miles, and so lousy when mid to high miles. Years ago this was the best design because it offered stabil tread and good grip when tiresow miles. Years ago, that was as good as it got.
However, new, modern designs of tires have new, better ways to have stabil tread blocks for stabil cornering and also have good traction. This allows performance to last longer, through most of tire's life. This also allows deeper sipes that last most of tire's life. This describes all the new generation ATs I recommended.
Also, all the currently best, new gen ATs have 5 rows of tread blocks, except for Goodyear Silent Armor, which I think has 6. More rows offers a few benefits. More edges for traction on wet pavement, ice, and packed snow, and more voids to reduce hydroplaning. Also, better lateral traction on all surfaces. Lateral traction is the most important thing for steering and safety. Also, the new tread designs don't have interlocking tread because interlocking tread clogs easily with snow and mud. For example, BFG AT has interlocking tread.
Interlocking tread was one of the ways old school ATs stabized treadblocks. The new ATs have better ways of stabizing treadblocks. The new ATs have paired treadblocks, which are tied together by a rubber common base. Paired treadblocks stabilizes tread for cornering, and it allows some self cleaning to clear snow and mud somewhat because its possible to have larger voids (and still have stabil tread for good handling/cornering).