I called TOYO about this specifically, because the stronger sidewalls in the RT over the AT2s was important. The gal said that the AT2s (all) only had a 2 ply sidewall, the F rating was because of 12 ply tread construction. I don't think she really understood about 2 or 3 ply sidewalls. I had to keep reminding her that my questions were concerning sidewall strength, not tread plys. For what its worth...I read hours of customer feedback on the NITTO ridge grapplers and the TOYO RTs. The TOYOs won out because of the 3 ply sidewall and the many customer comments that they had problems with the NITTOs chunking. The biggest downside to the RTs seems to be wet traction.