Comparison
225/35 R19 vs 255/40 R18
Minus-sizing from 225/35 R19 to 255/40 R18 pairs a smaller 18-inch wheel with more rubber between the rim and road. This tire combination moves rolling diameter well outside the usual OEM tolerance. Indicated speed will drift far enough that recalibration is worth considering. The taller sidewall adds cushioning over potholes and rougher roads, with a softer overall ride. The 3–5% diameter gap puts this in caution territory: doable on many cars, but verify clearance and consider recalibration.
TakePractical direction for winter wheels, chains, or rougher pavement where cushioning matters.
Quick math: 255/40 R18 is 21.1 mm taller than 225/35 R19, shifting the speedometer by +3.30%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+21.1 mm
3.30%
Speedometer at 100
103.3 km/h
+3.30% error
Ground clearance
+10.6 mm
ride height delta
Sidewall change
+23.3 mm
revs/km: 481.4
Permalink for this comparison:
/compare/225-35-r19-vs-255-40-r18Detailed comparison
| Metric | 225/35 R19 | 255/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 640.1 mm | 661.2 mm | +21.1 mm (+3.30%) |
| Sidewall height | 78.8 mm | 102.0 mm | +23.3 mm |
| Circumference | 2.011 m | 2.077 m | +66.3 mm |
| Revs / km | 497.3 | 481.4 | -15.9 |
| Ground clearance | reference | +10.6 mm | +10.6 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 103.3 km/h | +3.30 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 103.3 km/h after switching to 255/40 R18 — a +3.30% 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 +10.6 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
225/35 R19
Back to
255/40 R18
Drivers also compare
Closely-related fitments and plus-size swaps for 225/35 R19 and 255/40 R18.
225/45 R18 vs 255/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 0.23%
225/35 R19 vs 235/35 R19
Wider variation on the same rim — more grip, less clearance.
Δ 1.09%
235/45 R18 vs 255/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.12%
255/40 R18 vs 265/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.21%
245/40 R18 vs 255/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.22%
215/45 R18 vs 255/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.61%
255/40 R18 vs 275/35 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.74%
225/35 R19 vs 245/35 R19
Wider variation on the same rim — more grip, less clearance.
Δ 2.19%
Related topics