Tire Size Calculator

Decode tire size specifications (e.g. 215/60R16), calculate overall diameter and revs/mile, and compare stock vs custom replacement tires.

How to use this calculator

1. Enter tire code.
2. Read width, diameter, and revs/mile.
3. Compare 2 sizes for speedo error.

Formula & method

Metric Tire Equation

Diameter = (2 × (Width × Aspect/100) / 25.4) + Rim Inches

Tire math.

Example

215/60R16 = 26.16 in overall diameter.

Key insights

• Keep replacement diameter within 3%.

How to interpret your result

Overall Diameter

Total tire height.

Frequently asked questions

Tire numbers meaning?

215=width, 60=aspect %, 16=rim inches.

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