Comparison
235/45 R18 vs 255/35 R18
Switching from 235/45 R18 to 255/35 R18 drops the aspect ratio by 10 points on the same 18-inch wheel. This swap noticeably changes overall diameter compared to OEM. Less sidewall flex usually translates to crisper turn-in and a slightly stiffer ride over rough pavement.
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.
TakeSuits drivers who value sharper steering and appearance over outright ride softness.
Quick math: 255/35 R18 is 33.0 mm shorter than 235/45 R18, shifting the speedometer by -4.93%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
-33.0 mm
-4.93%
Speedometer at 100
95.1 km/h
-4.93% error
Ground clearance
-16.5 mm
ride height delta
Sidewall change
-16.5 mm
revs/km: 500.7
Permalink for this comparison:
/compare/235-45-r18-vs-255-35-r18Detailed comparison
| Metric | 235/45 R18 | 255/35 R18 | Difference |
|---|---|---|---|
| Overall diameter | 668.7 mm | 635.7 mm | -33.0 mm (-4.93%) |
| Sidewall height | 105.8 mm | 89.3 mm | -16.5 mm |
| Circumference | 2.101 m | 1.997 m | -103.7 mm |
| Revs / km | 476.0 | 500.7 | +24.7 |
| Ground clearance | reference | -16.5 mm | -16.5 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 95.1 km/h | -4.93 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 95.1 km/h after switching to 255/35 R18 — a -4.93% 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 -16.5 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
235/45 R18
Back to
255/35 R18
Drivers also compare
Closely-related fitments and plus-size swaps for 235/45 R18 and 255/35 R18.
235/45 R18 vs 265/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 0.07%
225/40 R18 vs 255/35 R18
Wider variation on the same rim — more grip, less clearance.
Δ 0.24%
215/40 R18 vs 255/35 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.03%
245/35 R18 vs 255/35 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.11%
235/45 R18 vs 255/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.12%
235/45 R18 vs 275/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.27%
235/45 R18 vs 245/45 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.35%
225/45 R18 vs 235/45 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.36%
Related topics