TIRE SIZE CALCULATOR

tire size calculator

InchesMetric
Diameter
Tread Width
Rim Diameter
Sidewall Height
Circumference
Revolutions
Tire diameter
Width
Dia.
Tire Size
Tire Circumference
Circ.
Rim
Height
Revs/Mile

Tire Size Conversion Explain

Tires measured in inches are easy to understand, but metric tires use more difficult to read. Here is the formula for calculating tire coefficients in inches:

  • Sidewall Height in Inches = ((Tire Width x Aspect Ratio)/100) / 25.4
  • Tire Diameter in Inches = (Rim Diameter x 2 + Wheel Diameter x25.4) / 25.4
  • Circumference in Inches = Tire Diameter x 3.14
  • Revolutions = 63,360 / Circumference

Tire Size Calculator FAQs:

How much difference in tire size is acceptable?

As a rule, you can replace the tires that are within ±3% of the Overall Tire diameter measurement of your current tires’ diameter — assuming your current tires are recommendations from your vehicle model

Do tire sizes need to be exact?

Tire width and rim diameter are the two main factors that determine tire and rim compatibility. As for the rim diameter, you will need to be sure that your tires and rims are an exact match, e.g. a 235/75R15 tire will only fit on a 15″ diameter rim. Tire width will be slightly more flexible equivalent to ±3%.

How much bigger can you go on tire size?

As a basic rule, it is safe to put tires up to 20 mm wider than the original tire on the stock rim. The actual width of the tire can vary depending on the width of the rim: The tire will expand by 5 mm when the rim width is increased by half an inch (12.7 mm).

What happens if one of my tires is a different size?

Having two different-sized tires on the same axle is not optimal. If the diameters of the two tires are close together then the rolling radius is roughly the same, temporarily, they probably won’t suffer any damage, but in the long run you run the risk of damaging your vehicle’s differential.

What matters most in tire size?

As a basic rule, the wider your tire width, the better your car will grip the road. As the width of the tire increases, it covers more surface area on the road. This increased contact with the road gives your vehicle more grip, increased handling and maneuverability

Can wrong-size tires damage the car?

If you install the wrong size tire on the rims, it can cause damage to the vehicle and is also a driving safety hazard.

Most Tire Size Conversions