Comparison
225/45 R18 vs 265/40 R18
Stepping from 225/45 R18 to 265/40 R18 keeps the 18-inch wheel but widens the section by 40 mm. This tire combination barely shifts the rolling circumference.
Dashboard speed shifts only marginally — within the noise of normal OEM tolerance. Less sidewall flex usually translates to crisper turn-in and a slightly stiffer ride over rough pavement. More tread on the ground tends to improve dry grip and stance, with a small fuel-economy and clearance tradeoff. Overall the swap sits inside the safe ±3% diameter window, so ABS, traction control and gearing behave normally.
TakeReasonable performance-leaning swap as long as fender and suspension clearance check out.
Quick math: 265/40 R18 is 9.5 mm taller than 225/45 R18, shifting the speedometer by +1.44%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+9.5 mm
1.44%
Speedometer at 100
101.4 km/h
+1.44% error
Ground clearance
+4.8 mm
ride height delta
Sidewall change
+4.8 mm
revs/km: 475.7
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/compare/225-45-r18-vs-265-40-r18Detailed comparison
| Metric | 225/45 R18 | 265/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 659.7 mm | 669.2 mm | +9.5 mm (+1.44%) |
| Sidewall height | 101.3 mm | 106.0 mm | +4.8 mm |
| Circumference | 2.073 m | 2.102 m | +29.8 mm |
| Revs / km | 482.5 | 475.7 | -6.8 |
| Ground clearance | reference | +4.8 mm | +4.8 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 101.4 km/h | +1.44 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 101.4 km/h after switching to 265/40 R18 — a +1.44% 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 +4.8 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
225/45 R18
Back to
265/40 R18
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