315/40R18 vs 255/45R19 tire size
255/45R19 vs 315/40R18, diameter
+0.4% taller
- Speedometer
- 59.8 mph
- At a true 60 mph
- Diameter
- 28.04 in
- Was 27.92 in
- Revs per mile
- 719
- Was 722
- 3% guideline
- Within
Car built for 315/40R18, now on 255/45R19.
315/40R18 and 255/45R19
| Measure | 315/40R18 | 255/45R19 | Difference |
|---|---|---|---|
| Width, mm | 315 | 255 | -60 |
| Sidewall, % of width | 40 | 45 | +5 |
| Rim, in | 18 | 19 | +1 |
| Section height, in | 4.96 | 4.52 | -0.44 |
| Diameter, in | 27.92 | 28.04 | +0.11 (+0.4%) |
| Circumference, in | 87.7 | 88.1 | +0.4 |
| Revs per mile | 722 | 719 | -3 (-0.4%) |
Fitting 255/45R19 instead of 315/40R18
Within the usual 3% diameter guideline.
- Needs 19 in wheels.
Cars with 315/40R18
Cars with 255/45R19
What this cannot tell you
Diameter within 3% is a common shop guideline, not a maker spec.
Load index, offset and clearance are not in this data.
- Two or more sources agree
- One source
- Model-level or estimate
- Sources differ