Title pretty much says it all. I got a flat on my right rear last night. Drove it to the dealership on the spare today and they said there's a 2mm(?) tread depth difference between a new tire and the ones already on my car, 10mm for the new vs 8mm on my current tires. The tires have 10,000 miles on them. They're the stock RE92s.
They said to replace all 4, or at least the back 2 because of the Subaru AWD system. Their reason was that different tire tread depths can cause wear in the AWD system becuase the new tire will rotate at a different rate than the old tires.
Is there any truth to this? I don't want to blow a ton of money on some BS. They want $200 per tire (mounted and balanced).