Comparison
225/50 R18 vs 245/45 R18
On the same 18-inch wheel, 245/45 R18 grows the section width by 20 mm versus 225/50 R18. This alternative fitment lands within OEM rolling-diameter tolerance. The shorter sidewall gives the tire a firmer, more responsive feel and sharpens steering input.
Dashboard speed shifts only marginally — within the noise of normal OEM tolerance. Diameter change stays inside the conservative ±3% safety window — an OEM-safe fitment on most vehicles.
TakeUseful when extra dry grip and stance matter more than a small fuel-economy hit.
Quick math: 245/45 R18 is 4.5 mm shorter than 225/50 R18, shifting the speedometer by -0.66%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-4.5 mm
-0.66%
Speedometer at 100
99.3 km/h
-0.66% error
Ground clearance
-2.3 mm
ride height delta
Sidewall change
-2.3 mm
revs/km: 469.7
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/compare/225-50-r18-vs-245-45-r18Detailed comparison
| Metric | 225/50 R18 | 245/45 R18 | Difference |
|---|---|---|---|
| Overall diameter | 682.2 mm | 677.7 mm | -4.5 mm (-0.66%) |
| Sidewall height | 112.5 mm | 110.3 mm | -2.3 mm |
| Circumference | 2.143 m | 2.129 m | -14.1 mm |
| Revs / km | 466.6 | 469.7 | +3.1 |
| Ground clearance | reference | -2.3 mm | -2.3 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 99.3 km/h | -0.66 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 99.3 km/h after switching to 245/45 R18 — a -0.66% 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 -2.3 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
225/50 R18
Back to
245/45 R18
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