I just picked up a descent set of tires super cheap...kinda like robbery. The have maybe 7/32 left. Anyways, the tread wear rating is different. Two are 280 and the other two are 160. Is that going to pose a problem with the center diff?
I wouldn't risk it, but that's just me. And not because of treadwear. Although treadwear kinda tells me that 160 is a high-performance tire and probably has stiffer sidewall = different effective rolling radius. However - if you don't have an LSD center diff will be ok if you put similar tires on one side, but that's probably not a good idea safety-wise.
^ also those higher performance tires will be stickier than the other ones which will cause a constant variation in grip. This to my knowledge is not good for the AWD system.
This I would not worry about, amount of slipping in the contact patch during steady cruising is not gonna cause significant difference in rotation speed. During turning - sure, but those aren't that long. Sidewall deformation would matter a lot more.
