Tread on the DRIVE axle, be it front or back usually wears faster, than a none drive axle. I guess this is why you need to rotate tires. I have only done mine once in 36000 miles, and both front and rear tire wear seem even at this point.
My last 2 pickups, a 1998 Chevy and a 2000 GMC both had worn out tires, (General) before 30,000. My current truck a 2003 GMC has lots of tread at 36,000 on it's Bridgestones. I should make 50K with no sweat!
2003 GMC 2500HD 4X4 D/A Ext. Cab
Propane Powered Honda EU2000i
Lots of Hot Sauce!
Air # 283