Tire Size Comparison Calculator
Input your factory tire size and your new tire size to instantly find out how it affects clearance, ride height, and speedometer reading.
| Spec | OEM | New |
|---|---|---|
| Diameter | 25.72" | 25.30" |
| Width | 9.65" | 10.43" |
| Circumference | 80.79" | 79.49" |
| Revs / Mile | 784 | 797 |
If your speedometer says 60 mph, you are actually traveling at:
Tire Fitment Check
This tool calculates tire diameter and width only. Verify fitment with your specific vehicle:
- Check your door jamb placard or owner manual for OEM sizes
- Offset, suspension, and body modifications affect clearance
- Load ratings and speed indices must match or exceed OEM specs
Methodology
Tire Diameter: Wheel Size + (2 × Sidewall Height)
Sidewall Height: Width(mm) × Aspect Ratio ÷ 100 ÷ 25.4
Frequently Asked Questions
Will changing tire size affect my speedometer accuracy?
Yes! Larger tires read lower on speedo; smaller tires read higher. Your speedometer is calibrated to OEM (stock) tire size. Use our speedometer error calculator to check if you're off.
Can I fit a different tire size without suspension changes?
Maybe. If aspect ratio stays similar (e.g., 235/45R18 to 245/45R18), fitment is usually fine. Drastically different sizes may cause rubbing, speedometer error, or handling changes.
What do the tire size numbers actually mean?
Example: 215/50R16 = width (215mm) / aspect ratio (50% of width = height) / construction (R=radial) / rim diameter (16 inches). Changing any number affects rolling diameter.
Disclaimer & Legal Notice
All tools and calculators provided by Lapsite are for informational and educational purposes only. While we strive for mathematical precision, these results are approximations and should not be used as the sole basis for critical engineering, financial, or safety decisions. Lapsite Ltd and its creators provide no warranty, express or implied, regarding the accuracy or fitness of these calculations for any specific use.Always double-check calculations independently, especially for safety-critical components such as brakes, suspension, or structural changes. By using these tools, you agree that Lapsite Ltd is not liable for any mechanical failure, financial loss, or injury resulting from the use of this data.
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