Comparison
245/45 R17 vs 265/40 R18
Plus-sizing from 245/45 R17 to 265/40 R18 keeps overall diameter close to factory while opening room for a larger 18-inch wheel. This swap trims or stretches rolling diameter by a small margin. Expect a slight but noticeable shift in indicated speed compared to the original tires. Expect a more planted steering feel, at the cost of some of the cushioning a taller sidewall provides. Overall the swap sits inside the safe ±3% diameter window, so ABS, traction control and gearing behave normally.
TakeA solid pick for drivers chasing a more aggressive stance without abandoning OEM rolling diameter.
Quick math: 265/40 R18 is 16.9 mm taller than 245/45 R17, shifting the speedometer by +2.59%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+16.9 mm
2.59%
Speedometer at 100
102.6 km/h
+2.59% error
Ground clearance
+8.5 mm
ride height delta
Sidewall change
-4.3 mm
revs/km: 475.7
Permalink for this comparison:
/compare/245-45-r17-vs-265-40-r18Detailed comparison
| Metric | 245/45 R17 | 265/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 652.3 mm | 669.2 mm | +16.9 mm (+2.59%) |
| Sidewall height | 110.3 mm | 106.0 mm | -4.3 mm |
| Circumference | 2.049 m | 2.102 m | +53.1 mm |
| Revs / km | 488.0 | 475.7 | -12.3 |
| Ground clearance | reference | +8.5 mm | +8.5 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 102.6 km/h | +2.59 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 102.6 km/h after switching to 265/40 R18 — a +2.59% 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 +8.5 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
245/45 R17
Back to
265/40 R18
Drivers also compare
Closely-related fitments and plus-size swaps for 245/45 R17 and 265/40 R18.
235/45 R18 vs 265/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 0.07%
225/50 R17 vs 245/45 R17
Wider variation on the same rim — more grip, less clearance.
Δ 0.69%
215/50 R17 vs 245/45 R17
Wider variation on the same rim — more grip, less clearance.
Δ 0.85%
265/40 R18 vs 275/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.20%
255/40 R18 vs 265/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.21%
245/45 R18 vs 265/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.25%
235/45 R17 vs 245/45 R17
Wider variation on the same rim — more grip, less clearance.
Δ 1.40%
225/45 R18 vs 265/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.44%
Related topics