275/80R24.5 vs 295/70R24.5
Going from one to the other changes the overall height by -2.5 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/80R24.5 | 295/70R24.5 | Change |
|---|---|---|---|
| Overall height | 41.8" | 40.8" | -2.5 % |
| Sidewall | 8.66" | 8.13" | -6.1 % |
| Section width | 275 mm | 295 mm | +7.3 % |
| Circumference | 131.4" | 128.1" | -2.5 % |
| Revs per mile | 482 | 495 | +2.5 % |
| Axle height | 20.91" | 20.38" | -13.5 mm |
| Approved rim width | 7.5–10" | 8.5–11" | overlap 8.5–10" |
Both are approved on a rim 8.5" to 10" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 275/80R24.5. Fit 295/70R24.5 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.2 mph | -0.8 |
| 50 mph | 48.7 mph | -1.3 |
| 70 mph | 68.2 mph | -1.8 |
| 90 mph | 87.7 mph | -2.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,746 on the road, so it over-counts by 254. At a true 70 mph the first turns 563 times a minute, the second 577.