305/65R16 vs 295/70R16
Going from one to the other changes the overall height by +2.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 305/65R16 | 295/70R16 | Change |
|---|---|---|---|
| Overall height | 31.6" | 32.3" | +2.1 % |
| Sidewall | 7.81" | 8.13" | +4.2 % |
| Section width | 305 mm | 295 mm | -3.3 % |
| Circumference | 99.3" | 101.3" | +2.1 % |
| Revs per mile | 638 | 625 | -2.1 % |
| Axle height | 15.81" | 16.13" | +8.3 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 305/65R16. Fit 295/70R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 51.0 mph | +1.0 |
| 70 mph | 71.4 mph | +1.4 |
| 90 mph | 91.8 mph | +1.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,206 on the road, so it under-counts by 206. At a true 70 mph the first turns 744 times a minute, the second 729.