freshayr
Sep 27th, 03, 1:28 PM
I am trying to calculate what gear I need for my speedo on a muncie 4 spd. does anyone know the revolutions per mile for P215/70R/15 tires?
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66 Beau Sep 27th, 03, 10:01 PM According to Goodrich, 776 revs per mile at 45 mph. See link.. http://www.bfgoodrichtires.com/assets/pdf/touring_ta_tr4.pdf Wes freshayr Sep 28th, 03, 9:00 AM thanks! DaleM Oct 2nd, 03, 8:20 AM I have an RPM calculator (http://www.chevellestuff.com/generic/rpm_calculator.htm) and a couple of links to speedometer guru sites that'll help with speedo gear selection. 69boo307 Oct 2nd, 03, 11:57 AM wouldn't it be the same # of revolutions per mile no matter how fast you're going? only thing different would be the time it takes to cover the mile. 66 Beau Oct 3rd, 03, 2:41 AM 69boo Actually no. Watch a car at the drags with some real soft sidewalls and low air pressure. Off the line the tires are wide & short. By the time they cross the finish line, they're much taller. It's one of the things that is accounted for when they're trying to determine the right gear ratios. The spinning of the tire causes it to grow in height and changes the revs per mile. Probably not that big a deal at legal speeds, but I imagine the wider the tire, the greater the tendancy. | ||