RustyRatRod said Calculate GEAR, RPM, MPH, TIRE DIAMETER Wallace Racing - Calculate RPM for given MPH, Rear Gear Ratio and Trans Gear Ratio Wallace Racing - Calculate Rear Gear Ratio for given MPH, RPM and Trans Gear Ratio RPM/MPH From Gear Ratio Calculator by Wallace Racing I really am not understanding why you're having issues. All of these calculators can help you reach what you're looking for, I believe.......which of course as always is as clear as mud. Click to expand...