225/65R17 vs 235/60R18 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 | 225/65R17 | 235/60R18 | Difference |
|---|---|---|---|
| Overall Diameter | 724.3 mm (28.5") | 739.2 mm (29.1") | +14.9 mm |
| Section Width | 225 mm (8.9") | 235 mm (9.3") | +10 mm |
| Sidewall Height | 146.3 mm | 141 mm | -5.3 mm |
| Circumference | 2275.5 mm | 2322.3 mm | +46.8 mm |
| Revolutions/Mile | 707 | 693 | -14 |
| Aspect Ratio | 65% | 60% | -5% |
| Rim Diameter | 17" | 18" | +1" |
Key Impact Summary
Speedometer Correction Table
When switching from 225/65R17 to 235/60R18, your speedometer will under-read. Here is the correction at common speeds:
| Speedometer Shows | Actual Speed (mph) | Difference |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 mph |
| 40 mph | 40.8 mph | +0.8 mph |
| 50 mph | 51 mph | +1 mph |
| 60 mph | 61.2 mph | +1.2 mph |
| 70 mph | 71.4 mph | +1.4 mph |
| 80 mph | 81.6 mph | +1.6 mph |
| 90 mph | 91.9 mph | +1.9 mph |
| 100 mph | 102.1 mph | +2.1 mph |
| 110 mph | 112.3 mph | +2.3 mph |
| 120 mph | 122.5 mph | +2.5 mph |
What This Swap Means
Wider tires (235/60R18): 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.
Shorter sidewall: The 5.3mm decrease in sidewall height improves steering response and cornering precision. However, ride quality becomes firmer and the wheels are more vulnerable to pothole damage. This is a common trade-off when upsizing wheels (plus-sizing).
Ground clearance: Increases by 7.5mm, providing slightly better approach angles for off-road driving and speed bump clearance.