255/60R18 vs 265/50R19
Diameter -2.04% · Speedo at 60 mph reads 58.8 mph actual · Ground clearance -7.8 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 265/50R19 mounted is:
Speedometer error: -2.05% · Odometer reads low by 2.05%
Full comparison
| Measurement | 255/60R18 | 265/50R19 | Delta |
|---|---|---|---|
| Overall diameter | 30.05" | 29.43" | -2.04% |
| Section width | 255 mm | 265 mm | +10 mm |
| Sidewall height | 153 mm | 132.5 mm | -20.50 mm |
| Rim diameter | 18" | 19" | +1" |
| Circumference | 2398 mm | 2349 mm | -49 mm |
| Revs / mile | 671 | 685 | 14 |
| Ground clearance change | -7.8 mm | ||
Questions about this swap
What is the diameter difference between 255/60R18 and 265/50R19?
265/50R19 is 2.04% smaller in overall diameter than 255/60R18 — a difference of 15.6 mm (0.61 inches).
How does 265/50R19 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 265/50R19 is 58.8 mph — an error of -2.05%.
Is it safe to replace 255/60R18 with 265/50R19?
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.