When I bought my '07 JKU last year it had ProComp 605/65R17 MTs on it. Very agressive and super traction. I don't know how long they had been on the rig but they were very hard and very noisey. Granted they are mud terrains and some of that is to be expected but when I had my Jeep at the dealer for an unrelated problem, I asked the mechanic about them. He said it is normal for ProComps to become hard over time causing more noise and stiffness. Additionally, the first time I took them off road for some serious rock crawling, I left allot of rubber chips on the rocks.
All that being said, I can't say how old they are and I do live in Arizona and the summer sun can be tough on tires.

I'm just glad I switched to Duratracs.

 

I had the all terrains in the past,they aren't very aggressive at all for an a/t tire. My buddy has the mud terrains, aggressive tire, loud on the road, and wear out faster than an a/t.

 

I had the 33" X-Terrains. The wore out very fast. They were aggressive at first, but I wouldn't get another pair for my Jeep.

 

I have 6,000 miles on my 33" X-treme AT's, and they barely look worn at all. I drive 120 miles to school and back on the highway, and I offroad frequently. I don't consider them to be loud compared to most other tires, even with a soft top. I never have traction problems. I did recently have to rebalance them, but that isn't a biggie. My husband has 12,000 miles on his and no complaints.

I would say it isn't a bad tire. I am happy with them!