actually 3 questions:
1. have the opportunity to purchase Y spoke 20's with tires that are mismatched: continentals upfront and michelins in back. Is this an issue for the AWD system? in general?
2. Any way to estimate how many miles are actually on the tires? seller is saying 12k miles...
3. i have 3rd row so no spare. What do others here do when swapping the rock hard runflats to regular tires? I'd rather not drive around with a tire in the back

although in the past 8 years and 4 cars I dont ever recall having to replace a tire... but murphy's law will strike - i just know it.