[McGillicuddy]

Thanks for the insight Denny, I actually just got the Black Max on Friday. Haven't had a chance to put it on yet. I bought it in 13.25 x 17 because it was super cheap and I thought it would be a cost effective test and a fine spare. I'll be replacing a 12.75 x 21 MWC Vortex(I think) that was only letting me turn 4500rpm. If it comes close to the desired rpm performance I'll order the 13.75 x 15 from PowerTech. Their MQF is apparently the Black Max equivalent in SST. If I could gain 1 mpg I'd be elated! That's another 30-40 miles of range!

Assuming the same geometry(or at least shape) what would be the expected performance trade-off on the bigger wheel with less pitch? Will I lose top speed but gain mpg with the bigger wheel or can such a correlation be made?

By the way I got the performance numbers you sent, apparently got lost in the mail. Pretty nice research. I'll use it as a guide to monitor my performance. Thanks. Never thought about how much slippage occurs at lower rpm. Definitely makes a strong case for a bigger wheel and more blades.

-Gillie