Free tools
Tire size calculator.
Decode any tire size, find plus-size options that keep your speedometer honest, and check exactly how far off you are when you swap to a different size. Instant, client-side, no signup.
Cross section
Not to absolute scale — proportions only.
Specs
Computed live as you type.
Section width225 mm8.86 in
Aspect ratio45%
Rim diameter17 in
Sidewall height101.3 mm3.99 in
Overall diameter24.97 in634.3 mm
Revolutions per mile808
Load index921,389 lbs max
Speed ratingH130 mph max
How to read a tire size
A size like 225/45R17 92H means: 225 mm section width, 45% aspect ratio (sidewall as a percentage of width), R for radial construction, 17-inch rim, 92 load index (1,389 lbs), and H speed rating (130 mph).
When you change wheel diameter, you want to keep the overall tire diameter within about ±3% of stock. Bigger swings throw off your speedometer, ABS, traction control, and may rub at full lock. This calculator does that math for you.