215/70R16 vs 205/70R16
Going from one to the other changes the overall height by -2.0 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/70R16 | 205/70R16 | Change |
|---|---|---|---|
| Overall height | 27.9" | 27.3" | -2.0 % |
| Sidewall | 5.93" | 5.65" | -4.7 % |
| Section width | 215 mm | 205 mm | -4.7 % |
| Circumference | 87.5" | 85.8" | -2.0 % |
| Revs per mile | 724 | 739 | +2.0 % |
| Axle height | 13.93" | 13.65" | -7.0 mm |
| Approved rim width | 6–8" | 5.5–7.5" | overlap 6–7.5" |
Both are approved on a rim 6" to 7.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 215/70R16. Fit 205/70R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.4 mph | -0.6 |
| 50 mph | 49.0 mph | -1.0 |
| 70 mph | 68.6 mph | -1.4 |
| 90 mph | 88.2 mph | -1.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,802 on the road, so it over-counts by 198. At a true 70 mph the first turns 845 times a minute, the second 862.