Comparison
225/55 R18 vs 235/65 R17
Minus-sizing from 225/55 R18 to 235/65 R17 pairs a smaller 17-inch wheel with more rubber between the rim and road. This wheel and tire pairing moves rolling diameter well outside the usual OEM tolerance. The speedometer error is noticeable and may warrant a recalibration if you rely on indicated speed. More sidewall typically improves comfort and curb protection, especially on city streets. Diameter delta falls in the cautious 3–5% range, where speedometer recalibration and a careful clearance check are worth doing.
TakeTypical choice for a dedicated winter or off-road setup where extra sidewall pays off.
Quick math: 235/65 R17 is 32.6 mm taller than 225/55 R18, shifting the speedometer by +4.63%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+32.6 mm
4.63%
Speedometer at 100
104.6 km/h
+4.63% error
Ground clearance
+16.3 mm
ride height delta
Sidewall change
+29.0 mm
revs/km: 431.7
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/compare/225-55-r18-vs-235-65-r17Detailed comparison
| Metric | 225/55 R18 | 235/65 R17 | Difference |
|---|---|---|---|
| Overall diameter | 704.7 mm | 737.3 mm | +32.6 mm (+4.63%) |
| Sidewall height | 123.8 mm | 152.8 mm | +29.0 mm |
| Circumference | 2.214 m | 2.316 m | +102.4 mm |
| Revs / km | 451.7 | 431.7 | -20.0 |
| Ground clearance | reference | +16.3 mm | +16.3 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 104.6 km/h | +4.63 km/h |
Verdict: warning
Between 3% and 5% — noticeable speedometer drift; recalibration may be advisable.
Speedometer impact
At a true 100 km/h, your dashboard will read 104.6 km/h after switching to 235/65 R17 — a +4.63% 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 +16.3 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 R18
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235/65 R17
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