255/85R16 vs 315/75R16
315/75R16 is outside the ±3% rule as a replacement for 255/85R16: the diameter differs by +4.64%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 315/75R16 on a car calibrated for 255/85R16, the speedometer reads 57.3 mph when you're really doing 60, and the odometer under-counts by 4.6%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.4 mph |
| 45 mph | 47.1 mph |
| 60 mph | 62.8 mph |
| 70 mph | 73.3 mph |
| 80 mph | 83.7 mph |
Other sizes close to 255/85R16
Questions
Can I replace 255/85R16 with 315/75R16?
315/75R16 is outside the ±3% rule as a replacement for 255/85R16: the diameter differs by +4.64%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 255/85R16 and 315/75R16?
315/75R16 is 1.54" taller and 60 mm wider; the sidewall is +0.77". At an indicated 60 mph you'd actually be doing 62.8 mph.
Will 315/75R16 fit on 255/85R16 wheels?
Both use a 16" rim, so the wheel diameter matches; check the wheel's width range for a 315 mm tire and the fender clearance.