Tire Size Calculator

Find overall tire diameter from its size code.

Section width

Aspect ratio (%)

Rim diameter

Overall diameter 24.972

Overall diameter 634.3

Sidewall height 101.25

Formula: diameter = rim + 2 × (width × aspect/100)

Step-by-step with your numbers:

1. Values used:

2. Section width = 225

3. Aspect ratio = 45 %

4. Rim diameter = 17

6. Overall diameter = 24.972

7. Overall diameter = 634.3

8. Sidewall height = (225 / 100) x 45 = 2.25 x 45 = 101.25

Did we solve your problem today?

Decode a tire size like 225/45R17 into its real diameter.

The math behind it

sidewall = width × aspect ÷ 100; diameter = rim (×25.4) + 2 × sidewall.

225/45R17 → ~25.0 in diameter.

Plus-sizing?

Keep overall diameter similar to avoid speedometer error.