235/65R18 vs 255/60R18 Side-by-side tire size comparison with specs and compatibility
This tire swap is within the safe 3% diameter threshold. It should not cause issues with speedometer accuracy, ABS, or traction control systems.
Full Specifications Comparison
| Specification | 235/65R18 | 255/60R18 | Difference |
|---|---|---|---|
| Overall Diameter | 762.7 mm (30") | 763.2 mm (30") | +0.5 mm |
| Section Width | 235 mm (9.3") | 255 mm (10") | +20 mm |
| Sidewall Height | 152.8 mm | 153 mm | +0.2 mm |
| Circumference | 2396.1 mm | 2397.7 mm | +1.6 mm |
| Revolutions/Mile | 672 | 671 | -1 |
| Aspect Ratio | 65% | 60% | -5% |
| Rim Diameter | 18" | 18" | 0" |
Key Impact Summary
Speedometer Correction Table
When switching from 235/65R18 to 255/60R18, your speedometer will under-read. Here is the correction at common speeds:
| Speedometer Shows | Actual Speed (mph) | Difference |
|---|---|---|
| 30 mph | 30 mph | 0 mph |
| 40 mph | 40 mph | 0 mph |
| 50 mph | 50 mph | 0 mph |
| 60 mph | 60 mph | 0 mph |
| 70 mph | 70 mph | 0 mph |
| 80 mph | 80.1 mph | +0.1 mph |
| 90 mph | 90.1 mph | +0.1 mph |
| 100 mph | 100.1 mph | +0.1 mph |
| 110 mph | 110.1 mph | +0.1 mph |
| 120 mph | 120.1 mph | +0.1 mph |
What This Swap Means
Wider tires (255/60R18): The 20mm wider contact patch provides better grip in dry conditions and improved cornering stability. However, wider tires increase rolling resistance slightly, which may affect fuel economy by 1-2%. They are also more susceptible to hydroplaning in wet conditions.
Taller sidewall: The 0.2mm increase in sidewall height provides a more comfortable ride by absorbing more road imperfections. Taller sidewalls also offer better protection against pothole damage to wheels. The trade-off is slightly less responsive steering feel.
Ground clearance: Increases by 0.3mm, providing slightly better approach angles for off-road driving and speed bump clearance.