285/80R24.5 vs 295/75R24.5
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 | 285/80R24.5 | 295/75R24.5 | Change |
|---|---|---|---|
| Overall height | 42.5" | 41.9" | -1.3 % |
| Sidewall | 8.98" | 8.71" | -3.0 % |
| Section width | 285 mm | 295 mm | +3.5 % |
| Circumference | 133.4" | 131.7" | -1.3 % |
| Revs per mile | 475 | 481 | +1.3 % |
| Axle height | 21.23" | 20.96" | -6.8 mm |
| Approved rim width | 8–10.5" | 8.5–11" | overlap 8.5–10.5" |
Both are approved on a rim 8.5" to 10.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 285/80R24.5. Fit 295/75R24.5 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.6 mph | -0.4 |
| 50 mph | 49.4 mph | -0.6 |
| 70 mph | 69.1 mph | -0.9 |
| 90 mph | 88.9 mph | -1.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,875 on the road, so it over-counts by 125. At a true 70 mph the first turns 554 times a minute, the second 561.