295/70R22 vs 315/65R22
Going from one to the other changes the overall height by -0.4 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 295/70R22 | 315/65R22 | Change |
|---|---|---|---|
| Overall height | 38.3" | 38.1" | -0.4 % |
| Sidewall | 8.13" | 8.06" | -0.8 % |
| Section width | 295 mm | 315 mm | +6.8 % |
| Circumference | 120.2" | 119.8" | -0.4 % |
| Revs per mile | 527 | 529 | +0.4 % |
| Axle height | 19.13" | 19.06" | -1.8 mm |
| Approved rim width | 8.5–11" | 8.5–11.5" | 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 295/70R22. Fit 315/65R22 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.9 mph | -0.1 |
| 50 mph | 49.8 mph | -0.2 |
| 70 mph | 69.7 mph | -0.3 |
| 90 mph | 89.7 mph | -0.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,964 on the road, so it over-counts by 36. At a true 70 mph the first turns 615 times a minute, the second 617.