Comparison
265/40 R18 vs 275/40 R18
275/40 R18 is a wider variation of 265/40 R18 on the same 18-inch rim, adding 10 mm of tread footprint. This wheel and tire pairing lands within OEM rolling-diameter tolerance. Dashboard speed shifts only marginally — within the noise of normal OEM tolerance. The wider section adds contact patch and lateral stability, while eating into fender and suspension clearance. Diameter change stays inside the conservative ±3% safety window — an OEM-safe fitment on most vehicles.
TakeReasonable performance-leaning swap as long as fender and suspension clearance check out.
Quick math: 275/40 R18 is 8.0 mm taller than 265/40 R18, shifting the speedometer by +1.20%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+8.0 mm
1.20%
Speedometer at 100
101.2 km/h
+1.20% error
Ground clearance
+4.0 mm
ride height delta
Sidewall change
+4.0 mm
revs/km: 470.0
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/compare/265-40-r18-vs-275-40-r18Detailed comparison
| Metric | 265/40 R18 | 275/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 669.2 mm | 677.2 mm | +8.0 mm (+1.20%) |
| Sidewall height | 106.0 mm | 110.0 mm | +4.0 mm |
| Circumference | 2.102 m | 2.127 m | +25.1 mm |
| Revs / km | 475.7 | 470.0 | -5.6 |
| Ground clearance | reference | +4.0 mm | +4.0 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 101.2 km/h | +1.20 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 101.2 km/h after switching to 275/40 R18 — a +1.20% 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 +4.0 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.
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265/40 R18
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275/40 R18
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