245/75R16 vs 255/70R16
Going from one to the other changes the overall height by -1.4 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 245/75R16 | 255/70R16 | Change |
|---|---|---|---|
| Overall height | 30.5" | 30.1" | -1.4 % |
| Sidewall | 7.23" | 7.03" | -2.9 % |
| Section width | 245 mm | 255 mm | +4.1 % |
| Circumference | 95.7" | 94.4" | -1.4 % |
| Revs per mile | 662 | 671 | +1.4 % |
| Axle height | 15.23" | 15.03" | -5.3 mm |
| Approved rim width | 7–9" | 7–9.5" | overlap 7–9" |
Both are approved on a rim 7" to 9" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 245/75R16. Fit 255/70R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.6 mph | -0.4 |
| 50 mph | 49.3 mph | -0.7 |
| 70 mph | 69.1 mph | -0.9 |
| 90 mph | 88.8 mph | -1.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,864 on the road, so it over-counts by 136. At a true 70 mph the first turns 772 times a minute, the second 783.
What drivers reported
245/75R16 carries 188 complaints. 255/70R16 carries 68 and 1 deaths.