265/65R17 vs 275/65R18 Side-by-side tire size comparison with specs and compatibility
This tire swap is between 3-5% diameter difference. Check for fender clearance and be aware of speedometer error. May require recalibration.
Full Specifications Comparison
| Specification | 265/65R17 | 275/65R18 | Difference |
|---|---|---|---|
| Overall Diameter | 776.3 mm (30.6") | 814.7 mm (32.1") | +38.4 mm |
| Section Width | 265 mm (10.4") | 275 mm (10.8") | +10 mm |
| Sidewall Height | 172.3 mm | 178.8 mm | +6.5 mm |
| Circumference | 2438.8 mm | 2559.5 mm | +120.7 mm |
| Revolutions/Mile | 660 | 629 | -31 |
| Aspect Ratio | 65% | 65% | 0% |
| Rim Diameter | 17" | 18" | +1" |
Key Impact Summary
Speedometer Correction Table
When switching from 265/65R17 to 275/65R18, your speedometer will under-read. Here is the correction at common speeds:
| Speedometer Shows | Actual Speed (mph) | Difference |
|---|---|---|
| 30 mph | 31.5 mph | +1.5 mph |
| 40 mph | 42 mph | +2 mph |
| 50 mph | 52.5 mph | +2.5 mph |
| 60 mph | 63 mph | +3 mph |
| 70 mph | 73.5 mph | +3.5 mph |
| 80 mph | 84 mph | +4 mph |
| 90 mph | 94.5 mph | +4.5 mph |
| 100 mph | 104.9 mph | +4.9 mph |
| 110 mph | 115.4 mph | +5.4 mph |
| 120 mph | 125.9 mph | +5.9 mph |
What This Swap Means
Wider tires (275/65R18): 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 19.2mm, providing slightly better approach angles for off-road driving and speed bump clearance.