According to my Big 10 tire pros, the Cooper LTZ tire comes in a 305/50/20 with the lesser ply-better-ride-build and will fit the stock hydraulic suspension on the factory 20s. I may give it a try. The spare should still fit under as well. They also have the 305/55/20 which is the higher ply version for airing down and puncture resistance for about $90 per tire more and this would require adjusting the height control sensors to clear and I am told some mild trimming of the flaps may be necessary. My truck came with 285/50/20 Dunlop street tires stock. Coopers were not really a big player when I had the 100 to work with because the Nitto's were sized better for the 18 wheel.
