265/30R19 vs 235/40R18
235/40R18 is a safe swap for 265/30R19 by the usual ±3% rule: the diameter differs by +0.56%.
Speedometer and odometer
With 235/40R18 on a car calibrated for 265/30R19, the speedometer reads 59.7 mph when you're really doing 60, and the odometer under-counts by 0.6%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.2 mph |
| 45 mph | 45.3 mph |
| 60 mph | 60.3 mph |
| 70 mph | 70.4 mph |
| 80 mph | 80.4 mph |
Other sizes close to 265/30R19
- 265/30R19 vs 225/40R18-0.69%
- 265/30R19 vs 235/40R19+4.52%
- 265/30R19 vs 255/35R19+3.04%
- 265/30R19 vs 255/35R18-0.92%
- 265/30R19 vs 245/35R19+1.95%
- 265/30R19 vs 225/40R19+3.27%
- 265/30R19 vs 235/35R19+0.86%
- 265/30R19 vs 265/35R18+0.17%
- 265/30R19 vs 265/35R19+4.13%
- 265/30R19 vs 285/30R19+1.87%
- 265/30R19 vs 225/35R19-0.23%
- 265/30R19 vs 305/30R19+3.74%
Questions
Can I replace 265/30R19 with 235/40R18?
235/40R18 is a safe swap for 265/30R19 by the usual ±3% rule: the diameter differs by +0.56%.
What's the difference between 265/30R19 and 235/40R18?
235/40R18 is 0.14" taller and 30 mm narrower; the sidewall is +0.57". At an indicated 60 mph you'd actually be doing 60.3 mph.
Will 235/40R18 fit on 265/30R19 wheels?
No — 265/30R19 needs a 19" wheel and 235/40R18 a 18" wheel. This is a plus/minus-size swap that changes wheels too.