Comparison
215/55 R17 vs 255/45 R18
Going from 215/55 R17 to 255/45 R18 steps up to a 18-inch rim while trimming sidewall to stay near OEM rolling diameter. This wheel and tire pairing 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. Extra width broadens the footprint for more grip, but check inner liner and strut clearance before fitting. The larger wheel shows more of the brake hardware and tightens up the wheel-gap look. Diameter change stays inside the conservative ±3% safety window — an OEM-safe fitment on most vehicles.
TakeCommon upgrade for sportier handling and a tighter wheel-gap look on the same vehicle.
Quick math: 255/45 R18 is 18.4 mm taller than 215/55 R17, shifting the speedometer by +2.75%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+18.4 mm
2.75%
Speedometer at 100
102.8 km/h
+2.75% error
Ground clearance
+9.2 mm
ride height delta
Sidewall change
-3.5 mm
revs/km: 463.5
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/compare/215-55-r17-vs-255-45-r18Detailed comparison
| Metric | 215/55 R17 | 255/45 R18 | Difference |
|---|---|---|---|
| Overall diameter | 668.3 mm | 686.7 mm | +18.4 mm (+2.75%) |
| Sidewall height | 118.3 mm | 114.8 mm | -3.5 mm |
| Circumference | 2.100 m | 2.157 m | +57.8 mm |
| Revs / km | 476.3 | 463.5 | -12.8 |
| Ground clearance | reference | +9.2 mm | +9.2 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 102.8 km/h | +2.75 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 102.8 km/h after switching to 255/45 R18 — a +2.75% 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 +9.2 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
215/55 R17
Back to
255/45 R18
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