Comparison
235/35 R19 vs 275/40 R18
275/40 R18 drops the rim from 19 to 18 inches versus 235/35 R19, trading wheel size for taller sidewall. This tire combination noticeably changes overall diameter compared to OEM. The speedometer error is noticeable and may warrant a recalibration if you rely on indicated speed. The taller sidewall adds cushioning over potholes and rougher roads, with a softer overall ride. The 3–5% diameter gap puts this in caution territory: doable on many cars, but verify clearance and consider recalibration.
TakePractical direction for winter wheels, chains, or rougher pavement where cushioning matters.
Quick math: 275/40 R18 is 30.1 mm taller than 235/35 R19, shifting the speedometer by +4.65%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+30.1 mm
4.65%
Speedometer at 100
104.7 km/h
+4.65% error
Ground clearance
+15.1 mm
ride height delta
Sidewall change
+27.8 mm
revs/km: 470.0
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/compare/235-35-r19-vs-275-40-r18Detailed comparison
| Metric | 235/35 R19 | 275/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 647.1 mm | 677.2 mm | +30.1 mm (+4.65%) |
| Sidewall height | 82.3 mm | 110.0 mm | +27.8 mm |
| Circumference | 2.033 m | 2.127 m | +94.6 mm |
| Revs / km | 491.9 | 470.0 | -21.9 |
| Ground clearance | reference | +15.1 mm | +15.1 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 104.7 km/h | +4.65 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 104.7 km/h after switching to 275/40 R18 — a +4.65% 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 +15.1 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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235/35 R19
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275/40 R18
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