335/30R18 vs 275/40R18
275/40R18 is a safe swap for 335/30R18 by the usual ±3% rule: the diameter differs by +2.89%.
Speedometer and odometer
With 275/40R18 on a car calibrated for 335/30R18, the speedometer reads 58.3 mph when you're really doing 60, and the odometer under-counts by 2.9%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.9 mph |
| 45 mph | 46.3 mph |
| 60 mph | 61.7 mph |
| 70 mph | 72.0 mph |
| 80 mph | 82.3 mph |
Other sizes close to 335/30R18
- 335/30R18 vs 225/45R18+0.23%
- 335/30R18 vs 245/40R18-0.76%
- 335/30R18 vs 225/40R18-3.19%
- 335/30R18 vs 225/50R17-0.21%
- 335/30R18 vs 245/45R18+2.96%
- 335/30R18 vs 235/45R18+1.60%
- 335/30R18 vs 235/40R18-1.98%
- 335/30R18 vs 225/50R18+3.65%
- 335/30R18 vs 245/45R17-0.90%
- 335/30R18 vs 255/35R19+0.44%
- 335/30R18 vs 255/35R18-3.42%
- 335/30R18 vs 255/40R18+0.46%
Questions
Can I replace 335/30R18 with 275/40R18?
275/40R18 is a safe swap for 335/30R18 by the usual ±3% rule: the diameter differs by +2.89%.
What's the difference between 335/30R18 and 275/40R18?
275/40R18 is 0.75" taller and 60 mm narrower; the sidewall is +0.37". At an indicated 60 mph you'd actually be doing 61.7 mph.
Will 275/40R18 fit on 335/30R18 wheels?
Both use a 18" rim, so the wheel diameter matches; check the wheel's width range for a 275 mm tire and the fender clearance.