Tire Size Calculator – Convert Tire Diameter, Height to Inches

Tire Size Calculator

tire size calculator

Overall Diameter
Tread Width
Rim Diameter
Sidewall Height
Section Width
Tire Size
Tire Circumference

Tire Size Conversion Explained

Tire Width Calculator

Tire width is measured at its thickest point, the distance between the inner sidewall’s and the outer sidewall’s widest point, also known as section width or tread width.

E.g. 235/70R15: Tire Width = 235 mm (9.6 In.)

tread width
Tire Width

Tire Sidewall Height Calculator

Tire Sidewall Height is measured from the rim to the outer edge of the tire’s tread, expressed as a percentage of tire width.

Sidewall Height = (Tire Width*Aspect Ratio)/100

E.g. 235/70R15: Sidewall Height = (275*70)/100 = 192.5 mm (7.6 in.)

sidewall height
Sidewall Height

Rim/Wheel Height Calculator

Rim/Wheel Height is measured from the rim to the outer edge of the tire’s tread, expressed as a percentage of tire width.

E.g. 235/70R15 Rim Height = 15 In.

Rim Diameter
Rim Height

Tire Diameter Calculator

Tire Diameter is measured from the bottom to the highest point at the top of a tire through its exact center when inflated and no load.

Tire Diameter = Rim Height + 2*Sidewall Height

E.g. 235/70R15: Tire Diameter = 15 + 2*7.6 = 30.2 In.

Tire Diameter
Tire Diameter

Tire circumference Calculator

Tire circumference is measured of the distance the tire covers in one full rotation.

Circumference = Tire Diameter x 3.14

E.g. 235/70R15: Circumference = 30.2*3.14 = 94.8 In.


Tire Revolutions Calculator

The performs revs/mile. Revolutions per mile indicate the number of times a tire rotates while it covers the distance of one mile.

Revs/mile = 63,360/Circumference

E.g. 235/70R15: Revs/mile = 63,360/94.8 = 668.4


Wheel & Tire Calculator FAQs:

How important is tire width?

The tire width will affect noise level, grip, comfort, and handling. Replacing with wider tires may improve your car’s grip and handling but it can also increase rolling resistance and decrease fuel efficiency.

How much tire size difference is acceptable?

As a rule, you can replace the tire within a 3% difference in tire diameter (height) of the OEM tire size. It’s better to consult with the tire mechanic before deciding to switch to a smaller or large tire size. You may refer to our Tire Size Chart and Tire Size Comparison to determine the suitable tire size for your vehicle.

What is the difference between wheel size and tire size?

Wheel/rim size refers to the diameter and width of the wheel/rim itself, while tire size refers to the diameter, width, and aspect ratio of the tire mounted on the wheel/rim.

Popular Tire Size Conversions

*Note that this tire calculator is for information purposes only, the result is an approximation, as tire manufacturers can have slight variations in their measurements. It’s recommended to refer to the vehicle manufacturer’s guidelines or consult with a tire mechanic to determine the correct tire size for your vehicle.