Comparison
245/40 R20 vs 255/35 R20
Stepping from 245/40 R20 to 255/35 R20 keeps the 20-inch wheel but widens the section by 10 mm. This alternative fitment moves rolling diameter a touch off the original spec. Expect a slight but noticeable shift in indicated speed compared to the original tires. The shorter sidewall gives the tire a firmer, more responsive feel and sharpens steering input. Diameter change stays inside the conservative ±3% safety window — an OEM-safe fitment on most vehicles.
TakeUseful when extra dry grip and stance matter more than a small fuel-economy hit.
Quick math: 255/35 R20 is 17.5 mm shorter than 245/40 R20, shifting the speedometer by -2.49%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-17.5 mm
-2.49%
Speedometer at 100
97.5 km/h
-2.49% error
Ground clearance
-8.8 mm
ride height delta
Sidewall change
-8.8 mm
revs/km: 463.7
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/compare/245-40-r20-vs-255-35-r20Detailed comparison
| Metric | 245/40 R20 | 255/35 R20 | Difference |
|---|---|---|---|
| Overall diameter | 704.0 mm | 686.5 mm | -17.5 mm (-2.49%) |
| Sidewall height | 98.0 mm | 89.3 mm | -8.8 mm |
| Circumference | 2.212 m | 2.157 m | -55.0 mm |
| Revs / km | 452.1 | 463.7 | +11.5 |
| Ground clearance | reference | -8.8 mm | -8.8 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 97.5 km/h | -2.49 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 97.5 km/h after switching to 255/35 R20 — a -2.49% 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 -8.8 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 R20
Back to
255/35 R20
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