255/60R18 vs 265/60R18
Diameter +1.57% · Speedo at 60 mph reads 60.9 mph actual · Ground clearance +6.0 mm
Generally safe — within the 3% tolerance
The diameter difference is ≤3%, which is the widely-accepted fitment tolerance for speedometer accuracy and ABS/traction-control calibration. Verify clearance and load rating with a tire professional before installing.
Speedometer effect
When the vehicle's speedometer (calibrated to 255/60R18) reads 60 mph, the actual speed with 265/60R18 mounted is:
Speedometer error: +1.57% · Odometer reads high by 1.57%
Full comparison
| Measurement | 255/60R18 | 265/60R18 | Delta |
|---|---|---|---|
| Overall diameter | 30.05" | 30.52" | +1.57% |
| Section width | 255 mm | 265 mm | +10 mm |
| Sidewall height | 153 mm | 159 mm | +6.00 mm |
| Rim diameter | 18" | 18" | +0" |
| Circumference | 2398 mm | 2435 mm | +38 mm |
| Revs / mile | 671 | 661 | -10 |
| Ground clearance change | +6.0 mm | ||
Questions about this swap
What is the diameter difference between 255/60R18 and 265/60R18?
265/60R18 is 1.57% larger in overall diameter than 255/60R18 — a difference of 12.0 mm (0.47 inches).
How does 265/60R18 affect the speedometer if the car was calibrated for 255/60R18?
When the speedometer reads 60 mph (calibrated for 255/60R18), the actual speed with 265/60R18 is 60.9 mph — an error of +1.57%.
Is it safe to replace 255/60R18 with 265/60R18?
Generally safe — within the 3% tolerance. The diameter difference is ≤3%, which is the widely-accepted fitment tolerance for speedometer accuracy and ABS/traction-control calibration. Verify clearance and load rating with a tire professional before installing.
All calculations use standard ETRTO formulas. Confirm fitment with a qualified tire professional and your vehicle's door-placard before purchasing.