Vibe Tools · Free tire size comparison
Tire Size Calculator
Compare two tire sizes side by side, from low-profile performance tires to 35s, 37s and 40s. See the difference in height, sidewall and width, and exactly what your speedometer will read.
Current tire
New tire
Front view · to scale
Side view · to scale
Speedometer check
Alternate sizes for
Calculated from the size on the sidewall. Real dimensions vary slightly by brand, tread depth and wheel width, and not every size is made by every brand. Want us to confirm a fitment? Ask our team.
How to read a tire size
Metric (275/35R20): 275 mm wide, sidewall 35% of the width (about 96 mm), R for radial, fits a 20" wheel.
Off-road (35x12.50R20): 35" tall overall, 12.5" wide, fits a 20" wheel. These flotation sizes are common on trucks and Jeeps, and the calculator converts between both formats.
Why overall diameter matters
Your speedometer, ABS, traction control and gearing are calibrated to the factory tire's overall diameter. Change it too much and the speedometer reads wrong and a taller tire can rub.
Plus sizing
Going up in wheel diameter while lowering the sidewall keeps the overall diameter about the same. A 245/40R19 to 255/35R20 adds an inch of wheel with only about a 1% change. The shorter sidewall sharpens steering but rides a bit firmer. The alternate sizes chart above lists every common size within 3% of your tire, with the closest matches highlighted.
Every tire is approved for a range of wheel widths, and we match tires to the exact width on every package. Unsure? Send us your wheel size. Changing wheels too? Try our wheel offset calculator.
Tire size FAQ
Can I put a different size tire on my car?
Usually, if the overall diameter stays within 1 to 2% and the tire is approved for your wheel width. Check clearance and load rating.
Will bigger tires change my speedometer?
Yes. A taller tire makes the speedometer read slower than your actual speed. The speedometer check above shows the exact difference.
What size is a 35 inch tire in metric?
Common metric equivalents are 315/70R17 and 305/70R18 (about 34.4" to 34.8"). Enter both sizes to compare exactly.
Is a wider tire always better?
Wider adds grip and a stronger look, but needs the right wheel width and fender clearance, and can add road noise.