Comparison
215/45 R18 vs 265/40 R18
On the same 18-inch wheel, 265/40 R18 grows the section width by 50 mm versus 215/45 R18. This setup trims or stretches rolling diameter by a small margin. Expect a more planted steering feel, at the cost of some of the cushioning a taller sidewall provides.
Expect a slight but noticeable shift in indicated speed compared to the original tires. 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: 265/40 R18 is 18.5 mm taller than 215/45 R18, shifting the speedometer by +2.84%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+18.5 mm
2.84%
Speedometer at 100
102.8 km/h
+2.84% error
Ground clearance
+9.3 mm
ride height delta
Sidewall change
+9.3 mm
revs/km: 475.7
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/compare/215-45-r18-vs-265-40-r18Detailed comparison
| Metric | 215/45 R18 | 265/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 650.7 mm | 669.2 mm | +18.5 mm (+2.84%) |
| Sidewall height | 96.8 mm | 106.0 mm | +9.3 mm |
| Circumference | 2.044 m | 2.102 m | +58.1 mm |
| Revs / km | 489.2 | 475.7 | -13.5 |
| Ground clearance | reference | +9.3 mm | +9.3 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 102.8 km/h | +2.84 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 102.8 km/h after switching to 265/40 R18 — a +2.84% 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 +9.3 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.
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215/45 R18
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265/40 R18
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