You guys that have went to a larger tire probably had to use an E load range tire. At least I did when I went to 275/65-20. There were little to no tires that size a C or D load range. Anyway, the E load range tire calls for 80psi at its max load rating. I'm trying different pressures to see what works the best between ride, wear, and proper pressure to carry the load (mainly on the rear axle). I'm coming up with 38-40psi. Anyone else have a preferred pressure?
It's a balance. When running oversized tires on stock rims, like I do now, there's a risk of 'crowning' if the tires are wider than stock. This can lead to premature wear along the centerline of the tread, and it is exaggerated if you run max pressure without a load. Meanwhile, if you run those same tires underinflated, you put additional stress on the sidewall of the tire, which compromises tire life and stability. My
factory-recommended tire pressures are 80 psi front / 55 psi rear (3/4-ton truck) when unloaded, and 80/80 when towing. I find that to be harsh. I'm also running (slightly) oversized tires and rarely tow, so I typically run 55/55. It's enough pressure to keep the tires wearing and performing correctly, but not so much that it beats me up.