The RE71 doesn't mind being pinched on a 6.5" rim, but it's not optimal and you won't get the performance figures that most are experiencing with them. They'll feel vague and squishy and won't turn in well. This tire likes a bit of stretch to it as they run on the wide side of normal for a 205/50. Honestly, you'd be better off looking for another 195/50, or try to find a 7.5" wheel. Cheap wheels are out there, but cheap( inexpensive not crappy) and different are not on the same side of the see saw. The TRMs that a lot of us are running are $99 each and can easily accommodate the 205/50 and get every last drop of performance out of them.
As for wear, I've got closed to 150 runs, and 5,000 total miles on them. They are quite interesting in the rain now that they are at 3/32", but we're much better when new. If I know it's going to rain hard and I don't have an event that coming weekend, the stocks go back on.
For a non serious autox car that needs better than 20,000 miles of life, I'd look at the Z2 for a high performance summer tire or another Bridgestone Product for a high performance all season.
