305/70R18 vs 325/65R18 tire size
325/65R18 vs 305/70R18, diameter
-0.5% shorter
- Speedometer
- 60.3 mph
- At a true 60 mph
- Diameter
- 34.63 in
- Was 34.81 in
- Revs per mile
- 582
- Was 579
- 3% guideline
- Within
Car built for 305/70R18, now on 325/65R18.
305/70R18 and 325/65R18
| Measure | 305/70R18 | 325/65R18 | Difference |
|---|---|---|---|
| Width, mm | 305 | 325 | +20 |
| Sidewall, % of width | 70 | 65 | -5 |
| Rim, in | 18 | 18 | 0 |
| Section height, in | 8.41 | 8.32 | -0.09 |
| Diameter, in | 34.81 | 34.63 | -0.18 (-0.5%) |
| Circumference, in | 109.4 | 108.8 | -0.6 |
| Revs per mile | 579 | 582 | +3 (+0.5%) |
Fitting 325/65R18 instead of 305/70R18
Within the usual 3% diameter guideline.
- 20 mm wider. Check rubbing at full lock.
Cars with 305/70R18
Cars with 325/65R18
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