The Pirelli MT-43 hybrid trials tire is quite a bit taller than the stock tire on the WR250R. I've been following the discussion on this tire closely. Other inmates here (just a few pages back on this thread - try reading it!) suggest that the difference is at least 1-tooth on the CS sprocket, or 3-4 teeth on the rear sprocket. To me, that is a lot! You should be prepared for the difference if you change just the rear tire and not your gearing.
1990 Honda NT-650 Hawk-GT
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