Tire Size Calculator, DOT Age

Read any sidewall in seconds. Type the code moulded into the rubber and get concrete numbers: size, load, speed rating and the date the tire was built.

SIZE CALCULATOR
Enter 225/45R17 and get overall diameter, section width, sidewall height, circumference and revolutions per kilometre. Metric, inch (33x12.50R15) and older notations are supported.

COMPARE TWO SIZES
The exact diameter difference in percent, speedometer error, the change in ground clearance and width, and a clear verdict on whether the swap works.

SIDEWALL DECODER
Load index in kilograms, speed rating in km/h, XL, Run Flat, M+S, 3PMSF, Load Range, UTQG - every segment explained in plain words.

DOT DATE AND TIRE AGE
Week and year of manufacture, the current age, the plant that built the tire and a verdict based on tire manufacturer guidance.

REFERENCE TABLES
Load index, speed index, UTQG grades and sidewall markings, based on UNECE R30, 49 CFR 574 and the public NHTSA plant code dataset.

Every formula is shown on screen, so you can check the result yourself. The app works fully offline, with no account and no registration. Available in 15+ languages. Free, supported by ads.