265/75R16 vs 275/65R18
Switching from 265/75R16 to 275/65R18 increases the overall diameter by 10.8 mm (1.3%). That is within the usual ±3% guideline.
| 265/75R16 | 275/65R18 | Difference (mm / revs) | |
|---|---|---|---|
| Section width | 265 mm | 275 mm | +10.0 |
| Sidewall height | 198.8 mm | 178.8 mm | -20.0 |
| Rim diameter | 406.4 mm | 457.2 mm | +50.8 |
| Overall diameter | 803.9 mm | 814.7 mm | +10.8 |
| Circumference | 2,525.5 mm | 2,559.5 mm | +34.0 |
| Revolutions | 396 per km | 391 per km | -5.0 |
Speedometer effect
With 275/65R18 fitted on a car calibrated for 265/75R16, the real speed when the speedometer shows:
| Speedometer shows | Actual speed |
|---|---|
| 50 km/h | 50.7 km/h |
| 80 km/h | 81.1 km/h |
| 100 km/h | 101.3 km/h |
| 120 km/h | 121.6 km/h |
Larger tires make the car go faster than the speedometer shows. Most speedometers also read slightly high from the factory.
Before you change size
- Check the sizes approved for your vehicle on the door-jamb placard or in the owner's manual.
- Check clearance to suspension, brakes and arches at full lock and full compression.
- Match or exceed the original load index and speed rating.
- Wider tires need an appropriate rim width; a 275 mm tire has a manufacturer-specified rim width range.
265/75R16 dimensions · 275/65R18 dimensions · Open in calculator