265/35R18 vs 315/30R18
315/30R18 is a safe swap for 265/35R18 by the usual ±3% rule: the diameter differs by +0.54%.
Speedometer and odometer
With 315/30R18 on a car calibrated for 265/35R18, the speedometer reads 59.7 mph when you're really doing 60, and the odometer under-counts by 0.5%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.2 mph |
| 45 mph | 45.2 mph |
| 60 mph | 60.3 mph |
| 70 mph | 70.4 mph |
| 80 mph | 80.4 mph |
Other sizes close to 265/35R18
- 265/35R18 vs 245/40R18+1.63%
- 265/35R18 vs 225/45R18+2.65%
- 265/35R18 vs 225/40R18-0.86%
- 265/35R18 vs 235/45R18+4.05%
- 265/35R18 vs 205/50R17-0.92%
- 265/35R18 vs 235/40R18+0.39%
- 265/35R18 vs 215/50R17+0.64%
- 265/35R18 vs 235/45R17+0.09%
- 265/35R18 vs 255/35R18-1.09%
- 265/35R18 vs 255/40R18+2.88%
- 265/35R18 vs 235/35R19+0.68%
- 265/35R18 vs 275/35R18+1.09%
Questions
Can I replace 265/35R18 with 315/30R18?
315/30R18 is a safe swap for 265/35R18 by the usual ±3% rule: the diameter differs by +0.54%.
What's the difference between 265/35R18 and 315/30R18?
315/30R18 is 0.14" taller and 50 mm wider; the sidewall is +0.07". At an indicated 60 mph you'd actually be doing 60.3 mph.
Will 315/30R18 fit on 265/35R18 wheels?
Both use a 18" rim, so the wheel diameter matches; check the wheel's width range for a 315 mm tire and the fender clearance.