About 10.000km's maximum with normal road use.theob said:4) How long can I expect they'll last? (non-track use)
Have the car aligned properly first and then change it so it has a little more front (negative) camber and a little more toe out. That should take care of most of the unsersteer in one go.I'm considering this purchase, because many of our roads are slippery, and 111R understeers sometimes more than wanted.
Going to A048R's is a very big and expensive step just to reduce some understeer.
Even if you want to go wider then I'd go for normal road tires in 185/50R16 front like the Dunlop SP9000 or the Toyo Proxes T1S.