When I lived in Alabama (near Birmingham), I had a Gen 1, ran Conti Road Attacks, one pair of Dunlops, got about 4500 miles per rear tire. We moved away. A few years later, we moved back. Bought the Gen 2. Ran Pilot Roads. Got about 5000 per rear. I recently tried the Road Attack 3s. Got 4500 out of the rear, just like with the Gen 1.
I met Sammax (Donnie, R.I.P.) and he and I pretty much rode together all the time for several years. Same roads. Never a pillion, same pace, but I tended to come into curves harder (brake harder), and come out harder. Donnie got about 10K out of rear tires. Also Pilot Roads. He rode a Gen 1. He was really smooth, and I tended to have the urge to get that extra acceleration sensation throughout the ride.
From my experience, I think riding style has a lot to do with it.