215/65R17 vs 235/60R18 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 | 215/65R17 | 235/60R18 | Difference |
|---|---|---|---|
| Overall Diameter | 711.3 mm (28") | 739.2 mm (29.1") | +27.9 mm |
| Section Width | 215 mm (8.5") | 235 mm (9.3") | +20 mm |
| Sidewall Height | 139.8 mm | 141 mm | +1.2 mm |
| Circumference | 2234.6 mm | 2322.3 mm | +87.7 mm |
| Revolutions/Mile | 720 | 693 | -27 |
| Aspect Ratio | 65% | 60% | -5% |
| Rim Diameter | 17" | 18" | +1" |
Key Impact Summary
Speedometer Correction Table
When switching from 215/65R17 to 235/60R18, your speedometer will under-read. Here is the correction at common speeds:
| Speedometer Shows | Actual Speed (mph) | Difference |
|---|---|---|
| 30 mph | 31.2 mph | +1.2 mph |
| 40 mph | 41.6 mph | +1.6 mph |
| 50 mph | 52 mph | +2 mph |
| 60 mph | 62.4 mph | +2.4 mph |
| 70 mph | 72.7 mph | +2.7 mph |
| 80 mph | 83.1 mph | +3.1 mph |
| 90 mph | 93.5 mph | +3.5 mph |
| 100 mph | 103.9 mph | +3.9 mph |
| 110 mph | 114.3 mph | +4.3 mph |
| 120 mph | 124.7 mph | +4.7 mph |
What This Swap Means
Wider tires (235/60R18): 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 1.2mm 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 14mm, providing slightly better approach angles for off-road driving and speed bump clearance.