Comparison
225/55 R17 vs 235/45 R18
Plus-sizing from 225/55 R17 to 235/45 R18 keeps overall diameter close to factory while opening room for a larger 18-inch wheel. This alternative fitment moves rolling diameter a touch off the original spec.
Expect a slight but noticeable shift in indicated speed compared to the original tires. Expect a more planted steering feel, at the cost of some of the cushioning a taller sidewall provides. Extra width broadens the footprint for more grip, but check inner liner and strut clearance before fitting. Visually, the bigger wheel fills the arch and gives the car a more aggressive stance. 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: 235/45 R18 is 10.6 mm shorter than 225/55 R17, shifting the speedometer by -1.56%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-10.6 mm
-1.56%
Speedometer at 100
98.4 km/h
-1.56% error
Ground clearance
-5.3 mm
ride height delta
Sidewall change
-18.0 mm
revs/km: 476.0
Permalink for this comparison:
/compare/225-55-r17-vs-235-45-r18Detailed comparison
| Metric | 225/55 R17 | 235/45 R18 | Difference |
|---|---|---|---|
| Overall diameter | 679.3 mm | 668.7 mm | -10.6 mm (-1.56%) |
| Sidewall height | 123.8 mm | 105.8 mm | -18.0 mm |
| Circumference | 2.134 m | 2.101 m | -33.3 mm |
| Revs / km | 468.6 | 476.0 | +7.4 |
| Ground clearance | reference | -5.3 mm | -5.3 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 98.4 km/h | -1.56 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 98.4 km/h after switching to 235/45 R18 — a -1.56% 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 -5.3 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.
Back to
225/55 R17
Back to
235/45 R18
Drivers also compare
Closely-related fitments and plus-size swaps for 225/55 R17 and 235/45 R18.
235/45 R18 vs 265/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 0.07%
235/45 R18 vs 255/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.12%
235/45 R18 vs 275/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.27%
235/45 R18 vs 245/45 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.35%
225/45 R18 vs 235/45 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.36%
215/60 R17 vs 225/55 R17
Wider variation on the same rim — more grip, less clearance.
Δ 1.52%
225/55 R17 vs 235/55 R17
Wider variation on the same rim — more grip, less clearance.
Δ 1.62%
215/55 R17 vs 225/55 R17
Wider variation on the same rim — more grip, less clearance.
Δ 1.65%
Related topics