245/70R24 vs 265/70R24
Going from one to the other changes the overall height by +2.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 245/70R24 | 265/70R24 | Change |
|---|---|---|---|
| Overall height | 37.5" | 38.6" | +2.9 % |
| Sidewall | 6.75" | 7.30" | +8.2 % |
| Section width | 245 mm | 265 mm | +8.2 % |
| Circumference | 117.8" | 121.3" | +2.9 % |
| Revs per mile | 538 | 522 | -2.9 % |
| Axle height | 18.75" | 19.30" | +14.0 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 265/70R24 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.9 mph | +0.9 |
| 50 mph | 51.5 mph | +1.5 |
| 70 mph | 72.1 mph | +2.1 |
| 90 mph | 92.6 mph | +2.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,294 on the road, so it under-counts by 294. At a true 70 mph the first turns 627 times a minute, the second 609.