Comparison
255/45 R20 vs 265/40 R20
Stepping from 255/45 R20 to 265/40 R20 keeps the 20-inch wheel but widens the section by 10 mm. This wheel and tire pairing trims or stretches rolling diameter by a small margin.
Expect a slight but noticeable shift in indicated speed compared to the original tires. Less sidewall flex usually translates to crisper turn-in and a slightly stiffer ride over rough pavement. The wider section adds contact patch and lateral stability, while eating into fender and suspension clearance. 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: 265/40 R20 is 17.5 mm shorter than 255/45 R20, shifting the speedometer by -2.37%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-17.5 mm
-2.37%
Speedometer at 100
97.6 km/h
-2.37% error
Ground clearance
-8.8 mm
ride height delta
Sidewall change
-8.8 mm
revs/km: 442.1
Permalink for this comparison:
/compare/255-45-r20-vs-265-40-r20Detailed comparison
| Metric | 255/45 R20 | 265/40 R20 | Difference |
|---|---|---|---|
| Overall diameter | 737.5 mm | 720.0 mm | -17.5 mm (-2.37%) |
| Sidewall height | 114.8 mm | 106.0 mm | -8.8 mm |
| Circumference | 2.317 m | 2.262 m | -55.0 mm |
| Revs / km | 431.6 | 442.1 | +10.5 |
| Ground clearance | reference | -8.8 mm | -8.8 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 97.6 km/h | -2.37 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 97.6 km/h after switching to 265/40 R20 — a -2.37% 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
255/45 R20
Back to
265/40 R20
Drivers also compare
Closely-related fitments and plus-size swaps for 255/45 R20 and 265/40 R20.
265/40 R20 vs 295/35 R20
Wider variation on the same rim — more grip, less clearance.
Δ 0.76%
255/45 R20 vs 295/40 R20
Wider variation on the same rim — more grip, less clearance.
Δ 0.88%
265/40 R20 vs 275/40 R20
Wider variation on the same rim — more grip, less clearance.
Δ 1.11%
245/45 R20 vs 265/40 R20
Wider variation on the same rim — more grip, less clearance.
Δ 1.17%
245/45 R20 vs 255/45 R20
Wider variation on the same rim — more grip, less clearance.
Δ 1.24%
255/45 R20 vs 275/40 R20
Wider variation on the same rim — more grip, less clearance.
Δ 1.29%
265/40 R20 vs 285/35 R20
Wider variation on the same rim — more grip, less clearance.
Δ 1.74%
245/40 R20 vs 265/40 R20
Wider variation on the same rim — more grip, less clearance.
Δ 2.27%
Related topics