Comparison
245/40 R19 vs 275/35 R18
Switching from 245/40 R19 to 275/35 R18 steps down to a 18-inch wheel — a familiar move for winter and dedicated all-terrain sets. This swap noticeably changes overall diameter compared to OEM.
Indicated speed will drift far enough that recalibration is worth considering. The shorter sidewall gives the tire a firmer, more responsive feel and sharpens steering input. The wider section adds contact patch and lateral stability, while eating into fender and suspension clearance. Minus-sizing keeps replacement costs down and opens up a wider range of winter and all-terrain tires. Diameter delta falls in the cautious 3–5% range, where speedometer recalibration and a careful clearance check are worth doing.
TakePractical direction for winter wheels, chains, or rougher pavement where cushioning matters.
Quick math: 275/35 R18 is 28.9 mm shorter than 245/40 R19, shifting the speedometer by -4.26%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
-28.9 mm
-4.26%
Speedometer at 100
95.7 km/h
-4.26% error
Ground clearance
-14.4 mm
ride height delta
Sidewall change
-1.8 mm
revs/km: 489.9
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/compare/245-40-r19-vs-275-35-r18Detailed comparison
| Metric | 245/40 R19 | 275/35 R18 | Difference |
|---|---|---|---|
| Overall diameter | 678.6 mm | 649.7 mm | -28.9 mm (-4.26%) |
| Sidewall height | 98.0 mm | 96.3 mm | -1.8 mm |
| Circumference | 2.132 m | 2.041 m | -90.8 mm |
| Revs / km | 469.1 | 489.9 | +20.9 |
| Ground clearance | reference | -14.4 mm | -14.4 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 95.7 km/h | -4.26 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 95.7 km/h after switching to 275/35 R18 — a -4.26% 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 -14.4 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
245/40 R19
Back to
275/35 R18
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