225/45R20 vs 215/45R20
Going from one to the other changes the overall height by -1.3 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 225/45R20 | 215/45R20 | Change |
|---|---|---|---|
| Overall height | 28.0" | 27.6" | -1.3 % |
| Sidewall | 3.99" | 3.81" | -4.4 % |
| Section width | 225 mm | 215 mm | -4.4 % |
| Circumference | 87.9" | 86.8" | -1.3 % |
| Revs per mile | 721 | 730 | +1.3 % |
| Axle height | 13.99" | 13.81" | -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 225/45R20. Fit 215/45R20 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.6 mph | -0.4 |
| 50 mph | 49.4 mph | -0.6 |
| 70 mph | 69.1 mph | -0.9 |
| 90 mph | 88.9 mph | -1.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,873 on the road, so it over-counts by 127. At a true 70 mph the first turns 841 times a minute, the second 852.
What drivers reported
225/45R20 carries 1 complaints. Nobody has filed one naming 215/45R20.