Tire Size Converter

Passenger tire sidewalls encode section width, aspect ratio, construction type, and wheel diameter in strings like 225/45R17, while light trucks add load range and flotation sizes such as 31x10.50R15 that describe outer diameter and width directly. Changing one parameter alters overall diameter, which affects speedometer accuracy, gear effective ratio, and fender clearance. Plus-sizing keeps diameter constant while widening tread and shrinking sidewall height for handling aesthetics.

Enthusiasts swapping winter sets, overlanders fitting all-terrain tires, and used car buyers verifying that aftermarket wheels match OEM rolling circumference all need conversion beyond reading the label. A diameter change of three percent can trigger traction control faults or ABS anomalies on modern vehicles calibrated at the factory.

European metric labels dominate globally, but American classic and off-road markets retain inch-first naming that confuses importers. Load index and speed rating letters cap safe operating conditions independent of size math yet must appear on replacements meeting homologation rules.

Revolutions per mile link tire size to odometer and ECU expectations; mismatched axles front to rear on some all-wheel-drive platforms mandate tight diameter tolerances to prevent driveline bind. Spare tires labeled temporary use often differ in diameter intentionally, with speed restrictions posted on the sidewall.

Use this converter when spec'ing lift kits, comparing plus-one upgrade options, or decoding mixed listings on international tire retailer sites before purchase and mounting.