Comparison
225/50 R18 vs 235/45 R18
On the same 18-inch wheel, 235/45 R18 grows the section width by 10 mm versus 225/50 R18. This setup shifts overall diameter slightly from OEM. Expect a slight but noticeable shift in indicated speed compared to the original tires. The shorter sidewall gives the tire a firmer, more responsive feel and sharpens steering input. Overall the swap sits inside the safe ±3% diameter window, so ABS, traction control and gearing behave normally.
TakeUseful when extra dry grip and stance matter more than a small fuel-economy hit.
Quick math: 235/45 R18 is 13.5 mm shorter than 225/50 R18, shifting the speedometer by -1.98%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-13.5 mm
-1.98%
Speedometer at 100
98.0 km/h
-1.98% error
Ground clearance
-6.8 mm
ride height delta
Sidewall change
-6.8 mm
revs/km: 476.0
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/compare/225-50-r18-vs-235-45-r18Detailed comparison
| Metric | 225/50 R18 | 235/45 R18 | Difference |
|---|---|---|---|
| Overall diameter | 682.2 mm | 668.7 mm | -13.5 mm (-1.98%) |
| Sidewall height | 112.5 mm | 105.8 mm | -6.8 mm |
| Circumference | 2.143 m | 2.101 m | -42.4 mm |
| Revs / km | 466.6 | 476.0 | +9.4 |
| Ground clearance | reference | -6.8 mm | -6.8 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 98.0 km/h | -1.98 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 98.0 km/h after switching to 235/45 R18 — a -1.98% 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 -6.8 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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225/50 R18
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235/45 R18
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