Comparison
245/35 R20 vs 255/40 R19
Switching from 245/35 R20 to 255/40 R19 steps down to a 19-inch wheel — a familiar move for winter and dedicated all-terrain sets. This setup lands within OEM rolling-diameter tolerance.
The speedometer offset is mild and well inside what most cars can tolerate without recalibration. The taller sidewall adds cushioning over potholes and rougher roads, with a softer overall ride. More tread on the ground tends to improve dry grip and stance, with a small fuel-economy and clearance tradeoff. The smaller wheel is also lighter and easier to find affordable winter rubber for. Overall the swap sits inside the safe ±3% diameter window, so ABS, traction control and gearing behave normally.
TakePractical direction for winter wheels, chains, or rougher pavement where cushioning matters.
Quick math: 255/40 R19 is 7.1 mm taller than 245/35 R20, shifting the speedometer by +1.04%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+7.1 mm
1.04%
Speedometer at 100
101.0 km/h
+1.04% error
Ground clearance
+3.5 mm
ride height delta
Sidewall change
+16.3 mm
revs/km: 463.6
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/compare/245-35-r20-vs-255-40-r19Detailed comparison
| Metric | 245/35 R20 | 255/40 R19 | Difference |
|---|---|---|---|
| Overall diameter | 679.5 mm | 686.6 mm | +7.1 mm (+1.04%) |
| Sidewall height | 85.8 mm | 102.0 mm | +16.3 mm |
| Circumference | 2.135 m | 2.157 m | +22.3 mm |
| Revs / km | 468.4 | 463.6 | -4.8 |
| Ground clearance | reference | +3.5 mm | +3.5 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 101.0 km/h | +1.04 km/h |
Verdict: excellent
Within ±3% — speedometer, ABS and traction control should behave normally.
Speedometer impact
At a true 100 km/h, your dashboard will read 101.0 km/h after switching to 255/40 R19 — a +1.04% 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 +3.5 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 R20
Back to
255/40 R19
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