Comparison
245/45 R19 vs 265/40 R18
Switching from 245/45 R19 to 265/40 R18 steps down to a 18-inch wheel — a familiar move for winter and dedicated all-terrain sets. This wheel and tire pairing noticeably changes overall diameter compared to OEM. The shorter sidewall gives the tire a firmer, more responsive feel and sharpens steering input.
Indicated speed will drift far enough that recalibration is worth considering. Diameter delta falls in the cautious 3–5% range, where speedometer recalibration and a careful clearance check are worth doing.
TakeTypical choice for a dedicated winter or off-road setup where extra sidewall pays off.
Quick math: 265/40 R18 is 33.9 mm shorter than 245/45 R19, shifting the speedometer by -4.82%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
-33.9 mm
-4.82%
Speedometer at 100
95.2 km/h
-4.82% error
Ground clearance
-16.9 mm
ride height delta
Sidewall change
-4.3 mm
revs/km: 475.7
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/compare/245-45-r19-vs-265-40-r18Detailed comparison
| Metric | 245/45 R19 | 265/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 703.1 mm | 669.2 mm | -33.9 mm (-4.82%) |
| Sidewall height | 110.3 mm | 106.0 mm | -4.3 mm |
| Circumference | 2.209 m | 2.102 m | -106.5 mm |
| Revs / km | 452.7 | 475.7 | +22.9 |
| Ground clearance | reference | -16.9 mm | -16.9 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 95.2 km/h | -4.82 km/h |
Verdict: warning
Between 3% and 5% — noticeable speedometer drift; recalibration may be advisable.
Speedometer impact
At a true 100 km/h, your dashboard will read 95.2 km/h after switching to 265/40 R18 — a -4.82% 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 -16.9 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 R19
Back to
265/40 R18
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