235/45R18 vs 305/30R19 tire size
305/30R19 vs 235/45R18, diameter
-0.5% shorter
- Speedometer
- 60.3 mph
- At a true 60 mph
- Diameter
- 26.20 in
- Was 26.33 in
- Revs per mile
- 770
- Was 766
- 3% guideline
- Within
Car built for 235/45R18, now on 305/30R19.
235/45R18 and 305/30R19
| Measure | 235/45R18 | 305/30R19 | Difference |
|---|---|---|---|
| Width, mm | 235 | 305 | +70 |
| Sidewall, % of width | 45 | 30 | -15 |
| Rim, in | 18 | 19 | +1 |
| Section height, in | 4.16 | 3.60 | -0.56 |
| Diameter, in | 26.33 | 26.20 | -0.12 (-0.5%) |
| Circumference, in | 82.7 | 82.3 | -0.4 |
| Revs per mile | 766 | 770 | +4 (+0.5%) |
Fitting 305/30R19 instead of 235/45R18
Within the usual 3% diameter guideline.
- Needs 19 in wheels.
- 70 mm wider. Check rubbing at full lock.
- Shorter sidewall: 0.6 in less.
Cars with 235/45R18
Cars with 305/30R19
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