315/65R24 vs 295/70R24
Going from one to the other changes the overall height by +0.3 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 315/65R24 | 295/70R24 | Change |
|---|---|---|---|
| Overall height | 40.1" | 40.3" | +0.3 % |
| Sidewall | 8.06" | 8.13" | +0.9 % |
| Section width | 315 mm | 295 mm | -6.3 % |
| Circumference | 126.0" | 126.5" | +0.3 % |
| Revs per mile | 503 | 501 | -0.3 % |
| Axle height | 20.06" | 20.13" | +1.8 mm |
| Approved rim width | 8.5–11.5" | 8.5–11" | overlap 8.5–11" |
Both are approved on a rim 8.5" to 11" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 315/65R24. Fit 295/70R24 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.1 mph | +0.1 |
| 50 mph | 50.2 mph | +0.2 |
| 70 mph | 70.2 mph | +0.2 |
| 90 mph | 90.3 mph | +0.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,034 on the road, so it under-counts by 34. At a true 70 mph the first turns 586 times a minute, the second 584.