285/40R24 vs 265/45R24
Going from one to the other changes the overall height by +1.3 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 285/40R24 | 265/45R24 | Change |
|---|---|---|---|
| Overall height | 33.0" | 33.4" | +1.3 % |
| Sidewall | 4.49" | 4.69" | +4.6 % |
| Section width | 285 mm | 265 mm | -7.0 % |
| Circumference | 103.6" | 104.9" | +1.3 % |
| Revs per mile | 612 | 604 | -1.3 % |
| Axle height | 16.49" | 16.69" | +5.3 mm |
| Approved rim width | 8–10.5" | 7.5–9.5" | overlap 8–9.5" |
Both are approved on a rim 8" to 9.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 285/40R24. Fit 265/45R24 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.4 mph | +0.4 |
| 50 mph | 50.6 mph | +0.6 |
| 70 mph | 70.9 mph | +0.9 |
| 90 mph | 91.1 mph | +1.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,125 on the road, so it under-counts by 125. At a true 70 mph the first turns 714 times a minute, the second 705.