Oh that's a good question, I chose E for reasons at the time. The ride is not rough, they are probably the least noisy mud tires I've had, handles fine, but heavier crosswinds or passing a semi tends to be white knuckle.I appreciate the review! Are yours the C-rated version? I'm guessing the main issue on the highway is noise, or does it wander a bit? I've driven mud tires that do have some tendency to wander.