275/55R20 vs 265/60R18Tire Size Comparison
The 4.4% diameter difference exceeds 3% and may affect speedometer accuracy.
Comparison Details
Speedometer Correction
When switching from 275/55R20 to 265/60R18, your speedometer will differ from actual speed.
| Speedometer | Actual Speed | Difference |
|---|---|---|
| 30 km/h | 28.7 km/h | -1.3 km/h |
| 40 km/h | 38.3 km/h | -1.7 km/h |
| 50 km/h | 47.8 km/h | -2.2 km/h |
| 60 km/h | 57.4 km/h | -2.6 km/h |
| 70 km/h | 67.0 km/h | -3.0 km/h |
| 80 km/h | 76.5 km/h | -3.5 km/h |
| 90 km/h | 86.1 km/h | -3.9 km/h |
| 100 km/h | 95.6 km/h | -4.4 km/h |
| 110 km/h | 105.2 km/h | -4.8 km/h |
| 120 km/h | 114.8 km/h | -5.2 km/h |
| 130 km/h | 124.3 km/h | -5.7 km/h |
Vehicles Using These Sizes
Vehicles with 275/55R20
Vehicles with 265/60R18
Individual Tire Size Details
Practical Guidance
The 4.4% diameter difference between 275/55R20 and 265/60R18 exceeds the standard 3% tolerance. While physically possible, this change will cause noticeable speedometer error and may affect ABS and traction control calibration. Consult a tire professional before making this switch.
The 3% diameter tolerance is a widely accepted industry guideline referenced by the ETRTO and most vehicle manufacturers. When in doubt, consult your vehicle's owner's manual or a qualified tire professional. For U.S. tire safety standards and recalls, see the NHTSA Tire Safety page.
Frequently Asked Questions
Use Caution. The overall diameter differs by -4.36%, width changes by -10mm.
Speedometer error will be -4.36%. At an indicated 100 km/h, actual speed is about 95.6 km/h.
Ground clearance changes by -17.6mm per side.