295/75R22.5 vs 305/70R22.5
Going from one to the other changes the overall height by -1.5 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 295/75R22.5 | 305/70R22.5 | Change |
|---|---|---|---|
| Overall height | 39.9" | 39.3" | -1.5 % |
| Sidewall | 8.71" | 8.41" | -3.5 % |
| Section width | 295 mm | 305 mm | +3.4 % |
| Circumference | 125.4" | 123.5" | -1.5 % |
| Revs per mile | 505 | 513 | +1.5 % |
| Axle height | 19.96" | 19.66" | -7.8 mm |
| Approved rim width | 8.5–11" | 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 295/75R22.5. Fit 305/70R22.5 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.5 mph | -0.5 |
| 50 mph | 49.2 mph | -0.8 |
| 70 mph | 68.9 mph | -1.1 |
| 90 mph | 88.6 mph | -1.4 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,847 on the road, so it over-counts by 153. At a true 70 mph the first turns 589 times a minute, the second 599.
What drivers reported
295/75R22.5 carries 16 complaints. Nobody has filed one naming 305/70R22.5.