Comparison
225/40 R18 vs 265/40 R18
On the same 18-inch wheel, 265/40 R18 grows the section width by 40 mm versus 225/40 R18. This alternative fitment noticeably changes overall diameter compared to OEM. More tread on the ground tends to improve dry grip and stance, with a small fuel-economy and clearance tradeoff.
The dashboard speed will be significantly off — plan on recalibration before daily use. The diameter gap exceeds 5%, which can affect speedometer accuracy, ABS calibration and final gearing — review with a professional first.
TakeTreat as a serious modification — verify clearance, recalibrate the speedometer and reassess load capacity.
Quick math: 265/40 R18 is 32.0 mm taller than 225/40 R18, shifting the speedometer by +5.02%.
Current Tire
New Tire
Ground line · scaled comparison
Not Recommended
Over 5% — speedometer & ABS may misread
Diameter change
+32.0 mm
5.02%
Speedometer at 100
105.0 km/h
+5.02% error
Ground clearance
+16.0 mm
ride height delta
Sidewall change
+16.0 mm
revs/km: 475.7
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/compare/225-40-r18-vs-265-40-r18Detailed comparison
| Metric | 225/40 R18 | 265/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 637.2 mm | 669.2 mm | +32.0 mm (+5.02%) |
| Sidewall height | 90.0 mm | 106.0 mm | +16.0 mm |
| Circumference | 2.002 m | 2.102 m | +100.5 mm |
| Revs / km | 499.5 | 475.7 | -23.9 |
| Ground clearance | reference | +16.0 mm | +16.0 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 105.0 km/h | +5.02 km/h |
Verdict: danger
Over 5% diameter difference — likely to affect speedometer accuracy, ABS calibration and gearing. Not recommended without professional review.
Speedometer impact
At a true 100 km/h, your dashboard will read 105.0 km/h after switching to 265/40 R18 — a +5.02% 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 +16.0 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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225/40 R18
Back to
265/40 R18
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