yeah, the numbers on the site or or conservative... I've never put a 22x12 on my plane but if I did I know it would spin a few hundred RPMs more than listed on the site... It says on the site 22x12 6600 on the 65cc but mine would spin more in the 7000's+ I just started running my engine at a 40 to 1 ratio, but still with lawnboy ashless. if I went up to 50 to 1 with a synthetic it would pick up some more...