235/50R18 vs 235/55R18 Side-by-side tire size comparison with specs and compatibility
Compatibility
+3.39% diameter difference
⚠ Swap with Caution
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 | 235/50R18 | 235/55R18 | Difference |
|---|---|---|---|
| Overall Diameter | 692.2 mm (27.3") | 715.7 mm (28.2") | +23.5 mm |
| Section Width | 235 mm (9.3") | 235 mm (9.3") | 0 mm |
| Sidewall Height | 117.5 mm | 129.3 mm | +11.8 mm |
| Circumference | 2174.6 mm | 2248.4 mm | +73.8 mm |
| Revolutions/Mile | 740 | 716 | -24 |
| Aspect Ratio | 50% | 55% | +5% |
| Rim Diameter | 18" | 18" | 0" |
Key Impact Summary
Ground Clearance
+11.8 mm
Speedometer Error
+3.39%
Width Change
0 mm
Sidewall Change
+11.8 mm
Speedometer Correction Table
When switching from 235/50R18 to 235/55R18, your speedometer will under-read. Here is the correction at common speeds:
| Speedometer Shows | Actual Speed (mph) | Difference |
|---|---|---|
| 30 mph | 31 mph | +1 mph |
| 40 mph | 41.4 mph | +1.4 mph |
| 50 mph | 51.7 mph | +1.7 mph |
| 60 mph | 62 mph | +2 mph |
| 70 mph | 72.4 mph | +2.4 mph |
| 80 mph | 82.7 mph | +2.7 mph |
| 90 mph | 93.1 mph | +3.1 mph |
| 100 mph | 103.4 mph | +3.4 mph |
| 110 mph | 113.7 mph | +3.7 mph |
| 120 mph | 124.1 mph | +4.1 mph |
What This Swap Means
Taller sidewall: The 11.8mm 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 11.8mm, providing slightly better approach angles for off-road driving and speed bump clearance.
Vehicles Using 235/50R18
Vehicles Using 235/55R18
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Individual Tire Specs
Frequently Asked Questions
This swap requires caution. The diameter difference is +3.39% (+23.5mm). This exceeds the recommended 3% threshold and may affect speedometer accuracy, ABS calibration, and could cause clearance issues.
Switching from 235/50R18 to 235/55R18 creates a +3.39% speedometer error. Your actual speed will be faster than displayed — at an indicated 60 mph, you'll actually be going 62.0 mph.
Switching from 235/50R18 to 235/55R18 changes ground clearance by +11.8mm. The vehicle will sit 11.8mm higher. Ground clearance change equals half the overall diameter difference.