265/75R19 vs 245/85R19
Going from one to the other changes the overall height by +2.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 265/75R19 | 245/85R19 | Change |
|---|---|---|---|
| Overall height | 34.6" | 35.4" | +2.2 % |
| Sidewall | 7.82" | 8.20" | +4.8 % |
| Section width | 265 mm | 245 mm | -7.5 % |
| Circumference | 108.9" | 111.2" | +2.2 % |
| Revs per mile | 582 | 570 | -2.2 % |
| Axle height | 17.32" | 17.70" | +9.5 mm |
| Approved rim width | 7.5–9.5" | 7–9" | overlap 7.5–9" |
Both are approved on a rim 7.5" to 9" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 265/75R19. Fit 245/85R19 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 51.1 mph | +1.1 |
| 70 mph | 71.5 mph | +1.5 |
| 90 mph | 91.9 mph | +1.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,216 on the road, so it under-counts by 216. At a true 70 mph the first turns 679 times a minute, the second 665.