Accurate & Verified
Calculations use standard tire math with specs cross-checked against our size library.
Tire Reference is a free resource for anyone researching tire upgrades, replacements, or wheel fitment. Whether you are shopping for all-terrain tires on a truck, plus-sizing a crossover, or planning a lift and regear, our tools turn sidewall codes into real numbers you can compare before you buy. Browse popular tire sizes, jump into side-by-side comparisons, or start with a vehicle lookup when you want OEM fitment context before exploring plus-size and off-road options.
Use our tire size calculator to convert metric and flotation sizes into overall tire diameter, section width, and revolutions per mile. Run a tire comparison to see diameter change, width difference, and speedometer correction between your current and new size. Search by tire diameter when you know the height you want, model wheel offset and backspacing for clearance, and estimate gear ratio changes so highway RPM and acceleration stay where you expect after a taller tire.
Every calculation follows standard ISO/ETRTO tire math—the same formulas used across the industry for nominal diameter, circumference, and rolling distance. Results are generated instantly in your browser with no signup, so you can validate fitment, vehicle performance, and gearing decisions with confidence at every step of your build. From daily-driver replacements to lifted trail rigs, Tire Reference keeps the math transparent, repeatable, and easy to share with your installer or shop.