Comparison
245/35 R19 vs 275/40 R18
Minus-sizing from 245/35 R19 to 275/40 R18 pairs a smaller 18-inch wheel with more rubber between the rim and road. This sizing approach moves rolling diameter well outside the usual OEM tolerance. The speedometer error is noticeable and may warrant a recalibration if you rely on indicated speed. Extra sidewall absorbs impacts more readily — a sensible bias for daily commuting and broken pavement. The 3–5% diameter gap puts this in caution territory: doable on many cars, but verify clearance and consider recalibration.
TakeTypical choice for a dedicated winter or off-road setup where extra sidewall pays off.
Quick math: 275/40 R18 is 23.1 mm taller than 245/35 R19, shifting the speedometer by +3.53%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+23.1 mm
3.53%
Speedometer at 100
103.5 km/h
+3.53% error
Ground clearance
+11.6 mm
ride height delta
Sidewall change
+24.3 mm
revs/km: 470.0
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/compare/245-35-r19-vs-275-40-r18Detailed comparison
| Metric | 245/35 R19 | 275/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 654.1 mm | 677.2 mm | +23.1 mm (+3.53%) |
| Sidewall height | 85.8 mm | 110.0 mm | +24.3 mm |
| Circumference | 2.055 m | 2.127 m | +72.6 mm |
| Revs / km | 486.6 | 470.0 | -16.6 |
| Ground clearance | reference | +11.6 mm | +11.6 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 103.5 km/h | +3.53 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 103.5 km/h after switching to 275/40 R18 — a +3.53% 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 +11.6 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
245/35 R19
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275/40 R18
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