245/70R19 vs 255/65R19
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 | 245/70R19 | 255/65R19 | Change |
|---|---|---|---|
| Overall height | 32.5" | 32.1" | -1.4 % |
| Sidewall | 6.75" | 6.53" | -3.4 % |
| Section width | 245 mm | 255 mm | +4.1 % |
| Circumference | 102.1" | 100.7" | -1.4 % |
| Revs per mile | 620 | 629 | +1.4 % |
| Axle height | 16.25" | 16.03" | -5.8 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 245/70R19. Fit 255/65R19 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 | 69.0 mph | -1.0 |
| 90 mph | 88.7 mph | -1.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,861 on the road, so it over-counts by 139. At a true 70 mph the first turns 724 times a minute, the second 734.
What drivers reported
245/70R19 carries 3 complaints. Nobody has filed one naming 255/65R19.