265/65R24 vs 245/65R24
Going from one to the other changes the overall height by -2.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 265/65R24 | 245/65R24 | Change |
|---|---|---|---|
| Overall height | 37.6" | 36.5" | -2.7 % |
| Sidewall | 6.78" | 6.27" | -7.5 % |
| Section width | 265 mm | 245 mm | -7.5 % |
| Circumference | 118.0" | 114.8" | -2.7 % |
| Revs per mile | 537 | 552 | +2.7 % |
| Axle height | 18.78" | 18.27" | -13.0 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 265/65R24. Fit 245/65R24 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.2 mph | -0.8 |
| 50 mph | 48.6 mph | -1.4 |
| 70 mph | 68.1 mph | -1.9 |
| 90 mph | 87.5 mph | -2.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,727 on the road, so it over-counts by 273. At a true 70 mph the first turns 626 times a minute, the second 644.