Adjust the inputs below. Results update as you type.
Format P[width]/[aspect ratio]R[wheel diameter]: 225/65R17 means 225mm wide, 65% aspect ratio, 17-inch rim. Sidewall height = width × aspect ratio / 100 = 225 × 0.65 = 146.25mm. Overall diameter = wheel diameter × 25.4 + 2 × sidewall = 431.8 + 292.5 = 724.3mm. Changing tire size affects speedometer accuracy and gearing. A 3% diameter change alters speedometer reading by 3%.
Overall diameter ≈ 632 mm (24.88 in)