Comparison
225/50 R17 vs 265/40 R18
Going from 225/50 R17 to 265/40 R18 steps up to a 18-inch rim while trimming sidewall to stay near OEM rolling diameter. This tire combination shifts overall diameter slightly from OEM.
The speedometer offset is small but measurable; worth keeping in mind if you watch the dash closely. Less sidewall flex usually translates to crisper turn-in and a slightly stiffer ride over rough pavement. The wider section adds contact patch and lateral stability, while eating into fender and suspension clearance. The larger wheel shows more of the brake hardware and tightens up the wheel-gap look. Overall the swap sits inside the safe ±3% diameter window, so ABS, traction control and gearing behave normally.
TakeCommon upgrade for sportier handling and a tighter wheel-gap look on the same vehicle.
Quick math: 265/40 R18 is 12.4 mm taller than 225/50 R17, shifting the speedometer by +1.89%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+12.4 mm
1.89%
Speedometer at 100
101.9 km/h
+1.89% error
Ground clearance
+6.2 mm
ride height delta
Sidewall change
-6.5 mm
revs/km: 475.7
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/compare/225-50-r17-vs-265-40-r18Detailed comparison
| Metric | 225/50 R17 | 265/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 656.8 mm | 669.2 mm | +12.4 mm (+1.89%) |
| Sidewall height | 112.5 mm | 106.0 mm | -6.5 mm |
| Circumference | 2.063 m | 2.102 m | +39.0 mm |
| Revs / km | 484.6 | 475.7 | -9.0 |
| Ground clearance | reference | +6.2 mm | +6.2 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 101.9 km/h | +1.89 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 101.9 km/h after switching to 265/40 R18 — a +1.89% 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 +6.2 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
225/50 R17
Back to
265/40 R18
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