275/65R18 vs 285/65R18 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 | 275/65R18 | 285/65R18 | Difference |
|---|---|---|---|
| Overall Diameter | 814.7 mm (32.1") | 827.7 mm (32.6") | +13 mm |
| Section Width | 275 mm (10.8") | 285 mm (11.2") | +10 mm |
| Sidewall Height | 178.8 mm | 185.3 mm | +6.5 mm |
| Circumference | 2559.5 mm | 2600.3 mm | +40.8 mm |
| Revolutions/Mile | 629 | 619 | -10 |
| Aspect Ratio | 65% | 65% | 0% |
| Rim Diameter | 18" | 18" | 0" |
Key Impact Summary
Speedometer Correction Table
When switching from 275/65R18 to 285/65R18, your speedometer will under-read. Here is the correction at common speeds:
| Speedometer Shows | Actual Speed (mph) | Difference |
|---|---|---|
| 30 mph | 30.5 mph | +0.5 mph |
| 40 mph | 40.6 mph | +0.6 mph |
| 50 mph | 50.8 mph | +0.8 mph |
| 60 mph | 61 mph | +1 mph |
| 70 mph | 71.1 mph | +1.1 mph |
| 80 mph | 81.3 mph | +1.3 mph |
| 90 mph | 91.4 mph | +1.4 mph |
| 100 mph | 101.6 mph | +1.6 mph |
| 110 mph | 111.8 mph | +1.8 mph |
| 120 mph | 121.9 mph | +1.9 mph |
What This Swap Means
Wider tires (285/65R18): 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 6.5mm 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 6.5mm, providing slightly better approach angles for off-road driving and speed bump clearance.