Comparison
265/35 R20 vs 275/40 R18
Switching from 265/35 R20 to 275/40 R18 steps down to a 18-inch wheel — a familiar move for winter and dedicated all-terrain sets. This sizing approach trims or stretches rolling diameter by a small margin.
Expect a slight but noticeable shift in indicated speed compared to the original tires. Extra sidewall absorbs impacts more readily — a sensible bias for daily commuting and broken pavement. Extra width broadens the footprint for more grip, but check inner liner and strut clearance before fitting. The smaller wheel is also lighter and easier to find affordable winter rubber for. Diameter change stays inside the conservative ±3% safety window — an OEM-safe fitment on most vehicles.
TakeTypical choice for a dedicated winter or off-road setup where extra sidewall pays off.
Quick math: 275/40 R18 is 16.3 mm shorter than 265/35 R20, shifting the speedometer by -2.35%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-16.3 mm
-2.35%
Speedometer at 100
97.6 km/h
-2.35% error
Ground clearance
-8.1 mm
ride height delta
Sidewall change
+17.3 mm
revs/km: 470.0
Permalink for this comparison:
/compare/265-35-r20-vs-275-40-r18Detailed comparison
| Metric | 265/35 R20 | 275/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 693.5 mm | 677.2 mm | -16.3 mm (-2.35%) |
| Sidewall height | 92.8 mm | 110.0 mm | +17.3 mm |
| Circumference | 2.179 m | 2.127 m | -51.2 mm |
| Revs / km | 459.0 | 470.0 | +11.0 |
| Ground clearance | reference | -8.1 mm | -8.1 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 97.6 km/h | -2.35 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 275/40 R18 — a -2.35% 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 -8.1 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.
Back to
265/35 R20
Back to
275/40 R18
Drivers also compare
Closely-related fitments and plus-size swaps for 265/35 R20 and 275/40 R18.
245/45 R18 vs 275/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 0.07%
265/35 R20 vs 305/30 R20
Wider variation on the same rim — more grip, less clearance.
Δ 0.36%
225/50 R18 vs 275/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 0.73%
265/35 R20 vs 275/35 R20
Wider variation on the same rim — more grip, less clearance.
Δ 1.01%
255/35 R20 vs 265/35 R20
Wider variation on the same rim — more grip, less clearance.
Δ 1.02%
265/40 R18 vs 275/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.20%
235/45 R18 vs 275/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.27%
255/45 R18 vs 275/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.38%
Related topics