Tire Size Calculator

How to Calculate Tire Size

Understanding tire size calculations is crucial for vehicle performance and safety. This calculator helps you determine various tire dimensions and compare different sizes.

Tire Size Formula

The main formulas used in tire size calculations are:

• Tire Height = (Section Width * Aspect Ratio / 100 * 2) + (Wheel Diameter * 25.4)
• Sidewall Height = Section Width * Aspect Ratio / 100
• Tire Circumference = π * Tire Height
• Revolutions per Mile = 63360 / Tire Circumference

Calculation Steps

1. Input the tire's section width, aspect ratio, and wheel diameter.
2. Calculate the sidewall height using the aspect ratio.
3. Determine the total tire height by adding the sidewall height to the wheel diameter.
4. Calculate the tire's circumference using the total height.
5. Compute revolutions per mile for speedometer accuracy.

Example Calculation

Let's calculate the dimensions for a 225/45R17 tire:

• Section Width: 225 mm
• Aspect Ratio: 45%
• Wheel Diameter: 17 inches

1. Sidewall Height: 225 * 0.45 = 101.25 mm
2. Total Tire Height: (101.25 * 2) + (17 * 25.4) = 634.3 mm or 24.97 inches
3. Tire Circumference: π * 24.97 = 78.44 inches
4. Revolutions per Mile: 63360 / 78.44 = 808 rev/mile

Tire Size Diagram