I use a home brew Microsoft Excel file. It looks like shown below. You fill in the green boxes and it does the rest. Send me a PM with your email address and I'll send you a copy.

By the way, the simple formula is Mph x gear ratio ÷ tire diameter in inches ÷ .002975 = rpm.
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Last edited by Bill Hanlon; 04/17/2024 3:18 AM.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.