225/65R16 vs 215/70R16
Going from one to the other changes the overall height by +1.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 225/65R16 | 215/70R16 | Change |
|---|---|---|---|
| Overall height | 27.5" | 27.9" | +1.2 % |
| Sidewall | 5.76" | 5.93" | +2.9 % |
| Section width | 225 mm | 215 mm | -4.4 % |
| Circumference | 86.4" | 87.5" | +1.2 % |
| Revs per mile | 733 | 724 | -1.2 % |
| Axle height | 13.76" | 13.93" | +4.3 mm |
| Approved rim width | 6–8.5" | 6–8" | overlap 6–8" |
Both are approved on a rim 6" to 8" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 225/65R16. Fit 215/70R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.4 mph | +0.4 |
| 50 mph | 50.6 mph | +0.6 |
| 70 mph | 70.9 mph | +0.9 |
| 90 mph | 91.1 mph | +1.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,122 on the road, so it under-counts by 122. At a true 70 mph the first turns 855 times a minute, the second 845.