Tire Size To Gear Ratio Calculator, ) Motorcycle speed and sprocket calculator with bike database for gearing, sprockets, tires and chains of over 1900 bikes. Also calculated is the new gearing you would need in order to return back to your original gear ratio when going to a bigger or smaller tire. Use this tire gear ratio chart to match tire size with confidence. This tire size gear ratio calculator helps you understand how different tire sizes affect your vehicle's performance. Use our gear ratio calculator to find the effective gear ratio your vehicle will have with a new tire size. Learn what works on-road and off-road, then pick the right setup today for your vehicle. Calculate the proper gear ratio for a tire size change. Enter the smallest and largest rear cog sizes you want to compare. Revolutions per mile = 63,360 ÷ rolling circumference (in inches) And rolling circumference is just π multiplied by the tire's overall diameter. (Round your result up or down to the nearest standard gear ratio below. 1qs, nl, mba6z, xkfln, 9a0l, sfig, 6k6nr, hs2t, phu, c1ou,