245/70R24 vs 265/65R24
Going from one to the other changes the overall height by +0.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 245/70R24 | 265/65R24 | Change |
|---|---|---|---|
| Overall height | 37.5" | 37.6" | +0.2 % |
| Sidewall | 6.75" | 6.78" | +0.4 % |
| Section width | 245 mm | 265 mm | +8.2 % |
| Circumference | 117.8" | 118.0" | +0.2 % |
| Revs per mile | 538 | 537 | -0.2 % |
| Axle height | 18.75" | 18.78" | +0.8 mm |
| Approved rim width | 7–9" | 7.5–9.5" | 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 245/70R24. Fit 265/65R24 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.0 mph | +0.0 |
| 50 mph | 50.1 mph | +0.1 |
| 70 mph | 70.1 mph | +0.1 |
| 90 mph | 90.1 mph | +0.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,016 on the road, so it under-counts by 16. At a true 70 mph the first turns 627 times a minute, the second 626.