Hey guys need some advicee here. Got a really good deal on a pair of good year slicks. However they are 31' tall & I've used 32' in the past. The total diameter difference is less than 5", doesn't sound like much. But on top end how much will that effect my rpm's up there?? Any input would be great. Thanks, Ken

I saw a 500 RPM loss at the finish line in the 1/4 mile (6500 RPM) by going from 101 inch circumference M/T 10.5x31x15W slicks to a set of 315x60x15 M/T Et Street Radials that where 96.0 inches circumference(7000 RPM), the slicks will grow a lot more than the radials will The car ran 134.6 MPH with both sets of tires on the car the same weekend, same weather

Fwiw, I think the Wallace racing website has a program that will show you the difference.

A former 32" tire, now a 31" tire of the same style and construction, RPM's will increase approximately 31/32, or an increase of 3.2%, about 210 RPM at 7000, assuming that the car could "pull" the former tire efficiently. The tire "flywheel weight" can also make a difference in finish line RPM's

Thanks a lot, I can live w/200 rpm more. No big deal there at all, but I am changing wheels as well. Will have to get a weight comparison between them. Don't think there will be a big change there. Going from Weld Pro Stars to Center Line Pro Stocks. Will see when I get them off of the car. Thanks again for the input. See ya, Ken