225/45R16 vs 215/45R16
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 | 225/45R16 | 215/45R16 | Change |
|---|---|---|---|
| Overall height | 24.0" | 23.6" | -1.5 % |
| Sidewall | 3.99" | 3.81" | -4.4 % |
| Section width | 225 mm | 215 mm | -4.4 % |
| Circumference | 75.3" | 74.2" | -1.5 % |
| Revs per mile | 841 | 854 | +1.5 % |
| Axle height | 11.99" | 11.81" | -4.5 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 225/45R16. Fit 215/45R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.6 mph | -0.4 |
| 50 mph | 49.3 mph | -0.7 |
| 70 mph | 69.0 mph | -1.0 |
| 90 mph | 88.7 mph | -1.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,852 on the road, so it over-counts by 148. At a true 70 mph the first turns 982 times a minute, the second 996.