Originally Posted by Semperfi24
I don't think it is ground breaking to suggest that the weight rating of traditional truck tires with a normal sidewall is higher than a low pro tire with a smaller sidewall. Maybe I'm wrong, but that is all I was getting at. When I see 18 wheelers with low pro tires I might change my mind. More sidewall = higher weight rating. But I don't claim to be all knowing, just seems logical to me
Here are the load ratings for typical 18" and 20" tires. Keep in mind that P rated passenger tires have a 10% lower capacity than stated when used on trucks.
Load Range 113= 2282 (2535 x.9) Total= 9128 (4 tires @ 2282 each)
114 (stock Goodyear rating) 2341 (2601 x .9) Total = 9364
116 (some SL and XL) 2480 (2756 x .9) Total = 9920
Load Range 111 (SL rating, standard from factory) = 2163 (2403 x .9) Total= 8652
117 (XL load range) = 2550 (2833 x .9) Total = 10,200
115 (LT LRD tire, so no 10% reduction- what I run) = 2679 Total = 10716
Basically what I'm seeing is that stock tires in either 18" or 20" have a higher load rating than the trucks GVWR by a substantial margin, so I see no reason to believe they would need to downgrade the rating on a 20" wheel option truck. I also found it interesting that the SL load range has a higher rating on the 18" (113-116 versus 111) than the 20", but in the XL rating, the 20" has a higher carrying capacity (117 versus 116). Of course, you can step up to a load range E in either and have substantially more carrying capacity than the stock load range. I wanted to stay with stock size and went with LRD tires as LRE aren't available in 275/55-20, but have 10,716 total carrying capacity even with those.