Comparison
245/35 R19 vs 255/45 R18
Switching from 245/35 R19 to 255/45 R18 steps down to a 18-inch wheel — a familiar move for winter and dedicated all-terrain sets. This setup moves rolling diameter well outside the usual OEM tolerance. The taller sidewall adds cushioning over potholes and rougher roads, with a softer overall ride.
The speedometer error is noticeable and may warrant a recalibration if you rely on indicated speed. 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: 255/45 R18 is 32.6 mm taller than 245/35 R19, shifting the speedometer by +4.98%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+32.6 mm
4.98%
Speedometer at 100
105.0 km/h
+4.98% error
Ground clearance
+16.3 mm
ride height delta
Sidewall change
+29.0 mm
revs/km: 463.5
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/compare/245-35-r19-vs-255-45-r18Detailed comparison
| Metric | 245/35 R19 | 255/45 R18 | Difference |
|---|---|---|---|
| Overall diameter | 654.1 mm | 686.7 mm | +32.6 mm (+4.98%) |
| Sidewall height | 85.8 mm | 114.8 mm | +29.0 mm |
| Circumference | 2.055 m | 2.157 m | +102.4 mm |
| Revs / km | 486.6 | 463.5 | -23.1 |
| Ground clearance | reference | +16.3 mm | +16.3 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 105.0 km/h | +4.98 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 105.0 km/h after switching to 255/45 R18 — a +4.98% 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 +16.3 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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245/35 R19
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255/45 R18
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