245/50R18 vs 315/40R18 tire size
315/40R18 vs 245/50R18, diameter
+1.0% taller
- Speedometer
- 59.4 mph
- At a true 60 mph
- Diameter
- 27.92 in
- Was 27.65 in
- Revs per mile
- 722
- Was 730
- 3% guideline
- Within
Car built for 245/50R18, now on 315/40R18.
245/50R18 and 315/40R18
| Measure | 245/50R18 | 315/40R18 | Difference |
|---|---|---|---|
| Width, mm | 245 | 315 | +70 |
| Sidewall, % of width | 50 | 40 | -10 |
| Rim, in | 18 | 18 | 0 |
| Section height, in | 4.82 | 4.96 | +0.14 |
| Diameter, in | 27.65 | 27.92 | +0.28 (+1.0%) |
| Circumference, in | 86.9 | 87.7 | +0.9 |
| Revs per mile | 730 | 722 | -7 (-1.0%) |
Fitting 315/40R18 instead of 245/50R18
Within the usual 3% diameter guideline.
- 70 mm wider. Check rubbing at full lock.
Cars with 245/50R18
Cars with 315/40R18
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