Yeah, somehow I have a feeling that most GM spec wheel/tire combos will be pretty close to each other by intent. Even if you do the conversion between the 22" spec tires and the 18" spec tires they're only within 1mph of each other ... plus keeping in mind that each spec tire has a recommended psi I wouldn't be surprised that it is on purpose to keep the height/attitude/ground clearance/body clearance/etc constant across all the different truck trims.
Seems to me anyway.
Seems to me anyway.