The Stovebolt Site Forums The Parking Lot Tons 'o Fun Cruising speed?

My '57 2 ton originally had a 7.20:1 rear end, factory governed RPM is 4000, with 9.00 or 10.00 x 22.5 tires it would do 45 - 50 mph. I now have a 2 speed differential with 6.80:1 and 8.10:1 ratios, 10R-22.5 drive tires at approximately 41 inches tall, it's pretty happy at 55mph and can hit 63 mph at 4000+ rpm. My speedometer is roughly 2 - 3mph slow but the GPS gives me the above-mentioned speed.