What are tire revolutions per mile used for?
Revolutions per mile helps calculate speedometer accuracy, gear ratios, and fuel economy when changing tire sizes. It's essential for performance tuning and ensuring accurate vehicle readings.
Why do revolutions per mile vary with tire size?
Larger diameter tires cover more ground per revolution, resulting in fewer revolutions per mile. Smaller tires require more revolutions to travel the same distance.
How accurate are these calculations?
The calculations are mathematically precise based on tire dimensions. However, actual revolutions may vary by about 3% under vehicle load due to tire deformation and road conditions.
Can I use this for metric tire sizes?
Yes, enter the section width in millimeters and aspect ratio as shown on the tire sidewall. The rim diameter should be converted to inches if marked in other units.
What happens if I change tire size?
Changing tire size affects speedometer readings, odometer accuracy, and vehicle performance. Larger tires typically reduce revolutions per mile and may cause speedometer to read slower than actual speed.
How do I calculate sidewall height?
Sidewall height equals section width multiplied by aspect ratio divided by 100. For example, 225mm × 65% = 146.25mm sidewall height. You might also find our Tire Wear Life Calculator useful.