255/70R18 vs 265/70R17 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 | 255/70R18 | 265/70R17 | Difference |
|---|---|---|---|
| Overall Diameter | 814.2 mm (32.1") | 802.8 mm (31.6") | -11.4 mm |
| Section Width | 255 mm (10") | 265 mm (10.4") | +10 mm |
| Sidewall Height | 178.5 mm | 185.5 mm | +7 mm |
| Circumference | 2557.9 mm | 2522.1 mm | -35.8 mm |
| Revolutions/Mile | 629 | 638 | +9 |
| Aspect Ratio | 70% | 70% | 0% |
| Rim Diameter | 18" | 17" | -1" |
Key Impact Summary
Speedometer Correction Table
When switching from 255/70R18 to 265/70R17, your speedometer will over-read. Here is the correction at common speeds:
| Speedometer Shows | Actual Speed (mph) | Difference |
|---|---|---|
| 30 mph | 29.6 mph | -0.4 mph |
| 40 mph | 39.4 mph | -0.6 mph |
| 50 mph | 49.3 mph | -0.7 mph |
| 60 mph | 59.2 mph | -0.8 mph |
| 70 mph | 69 mph | -1 mph |
| 80 mph | 78.9 mph | -1.1 mph |
| 90 mph | 88.7 mph | -1.3 mph |
| 100 mph | 98.6 mph | -1.4 mph |
| 110 mph | 108.5 mph | -1.5 mph |
| 120 mph | 118.3 mph | -1.7 mph |
What This Swap Means
Wider tires (265/70R17): The 10mm 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 7.0mm 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: Decreases by 5.7mm, lowering the center of gravity slightly which can improve handling stability.