Good tool.[sm=thumbup.gif]
I use concrete runways, shortens both sides evenly.
BTW what do you run a 21x8 on? When it warms up a little around here I'm going to try the 20x8 20x10, and 21x8 BME props I just bought on my 50, 60 and 62 cc engines. I want to see if getting them spinning about 8000 rpm will make more pull than the 7200 I get with a 22x8.