X5 22” staggered tire replacement - just rear or all 4?
My X5 Xdrive40i with M Sport package is currently running the 22” staggered OEM Continental Premium Contact summer tires with around 25k miles on them. My rear tires are definitely due for replacement (3/32), and the local Firestone tire shop is telling me that my front (7/32) tires are still good. They are recommending that I only replace the rear 2 and said the tread depth difference won’t be an issue when I asked if this could cause premature wear on the drivetrain/transfers case. While I’d like to believe them, the guy also told me that it would be fine to replace the rear tires with all season Pirellis while leaving on the summers in the front. I don’t know much about tires, but I feel like that CAN’T be right, so I’m questioning his expertise. With the rear tires wearing faster, is it silly to throw away the front tires that still have a good amount of life on them, or not worth risking potential drivetrain damage? My husband thinks we should just replace the rear. I’m sure that if I ask the dealer they will tell me I need 4 new ones. Any advice is appreciated!