Just brought a new Chev Silvarado 1500 with 20" Goodyear Eagle tires. When doing a little research on the tires, which I wish I had done before buying the truck, found out they're passenger car tires....
Bilstar1, I had an 04 Sierra that came with the factory 20's. I ran 90,000 miles on that truck and about 30,000 of that was towing 6300+ pounds. I also hauled over 2k in the bed many times (not when towing) and never had a tire issue. I hated the Goodyears as they were poor in the rain and poorer in snow. I dumped them at 30000 for a set of Michelin's that had much better traction. My brother has a '11 Sierra with the factory 20's towing 6500 lbs with no problems. I went up to a 2500HD.