265/55R24 vs 245/55R24
Going from one to the other changes the overall height by -2.4 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 265/55R24 | 245/55R24 | Change |
|---|---|---|---|
| Overall height | 35.5" | 34.6" | -2.4 % |
| Sidewall | 5.74" | 5.31" | -7.5 % |
| Section width | 265 mm | 245 mm | -7.5 % |
| Circumference | 111.5" | 108.7" | -2.4 % |
| Revs per mile | 568 | 583 | +2.4 % |
| Axle height | 17.74" | 17.31" | -11.0 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 265/55R24. Fit 245/55R24 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.3 mph | -0.7 |
| 50 mph | 48.8 mph | -1.2 |
| 70 mph | 68.3 mph | -1.7 |
| 90 mph | 87.8 mph | -2.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,756 on the road, so it over-counts by 244. At a true 70 mph the first turns 663 times a minute, the second 680.