215/50R17 vs 225/45R17
Going from one to the other changes the overall height by -1.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/50R17 | 225/45R17 | Change |
|---|---|---|---|
| Overall height | 25.5" | 25.0" | -1.9 % |
| Sidewall | 4.23" | 3.99" | -5.8 % |
| Section width | 215 mm | 225 mm | +4.7 % |
| Circumference | 80.0" | 78.5" | -1.9 % |
| Revs per mile | 792 | 808 | +1.9 % |
| Axle height | 12.73" | 12.49" | -6.3 mm |
| Approved rim width | 6–8" | 6–8.5" | 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 215/50R17. Fit 225/45R17 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 | 88.3 mph | -1.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,807 on the road, so it over-counts by 193. At a true 70 mph the first turns 924 times a minute, the second 942.