Comparison
225/55 R17 vs 235/50 R18
Going from 225/55 R17 to 235/50 R18 steps up to a 18-inch rim while trimming sidewall to stay near OEM rolling diameter. This setup trims or stretches rolling diameter by a small margin. The shorter sidewall gives the tire a firmer, more responsive feel and sharpens steering input.
Expect a slight but noticeable shift in indicated speed compared to the original tires. Overall the swap sits inside the safe ±3% diameter window, so ABS, traction control and gearing behave normally.
TakeA solid pick for drivers chasing a more aggressive stance without abandoning OEM rolling diameter.
Quick math: 235/50 R18 is 12.9 mm taller than 225/55 R17, shifting the speedometer by +1.90%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+12.9 mm
1.90%
Speedometer at 100
101.9 km/h
+1.90% error
Ground clearance
+6.5 mm
ride height delta
Sidewall change
-6.3 mm
revs/km: 459.9
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/compare/225-55-r17-vs-235-50-r18Detailed comparison
| Metric | 225/55 R17 | 235/50 R18 | Difference |
|---|---|---|---|
| Overall diameter | 679.3 mm | 692.2 mm | +12.9 mm (+1.90%) |
| Sidewall height | 123.8 mm | 117.5 mm | -6.3 mm |
| Circumference | 2.134 m | 2.175 m | +40.5 mm |
| Revs / km | 468.6 | 459.9 | -8.7 |
| Ground clearance | reference | +6.5 mm | +6.5 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 101.9 km/h | +1.90 km/h |
Verdict: excellent
Within ±3% — speedometer, ABS and traction control should behave normally.
Speedometer impact
At a true 100 km/h, your dashboard will read 101.9 km/h after switching to 235/50 R18 — a +1.90% offset. Use the speedometer error calculator to recheck for other indicated speeds, and the speedometer error guide for the full background.
Ground clearance change
The new tire's half-diameter changes ride height by +6.5 mm. Small differences are absorbed by suspension travel, but anything beyond ±10 mm can affect headlight aim, fender clearance and bump-stop margin. See the plus-sizing guide before committing.
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225/55 R17
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235/50 R18
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