I posted my findings on this at some length last year ( search : Tyres and geometry - money well spent). The RX will eat tyres unless properly set up. All mine needed was tracking to get well over 22,500 miles from the front tyres. Not bad in my opinion - especially when you see how much two tyres cost!
Alan
Agree
Get the car set up by someone who knows what they are doing, watch for any signs of uneven wear (avid pot holes etc where practical) than have any deviation corrected promptly.
22,500 mils and more is quite easily attained.