I do only half days on the track since it's extremely difficult to get away for a whole day for me.
Almost every time I do 70-80miles on the track. (I reset my trip computer just to get amused with the 7.5-8.0 miles/gallon reading)
So far I've got about 230miles on the BFG -R1 and I think I have another 250-300 miles to go.
So I guess I have about 500-550 miles life expectancy with my driving on MAM per set of BFG-R1.