225/45R15 vs 215/50R15
Going from one to the other changes the overall height by +2.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 225/45R15 | 215/50R15 | Change |
|---|---|---|---|
| Overall height | 23.0" | 23.5" | +2.1 % |
| Sidewall | 3.99" | 4.23" | +6.2 % |
| Section width | 225 mm | 215 mm | -4.4 % |
| Circumference | 72.2" | 73.7" | +2.1 % |
| Revs per mile | 878 | 860 | -2.1 % |
| Axle height | 11.49" | 11.73" | +6.3 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 225/45R15. Fit 215/50R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 51.1 mph | +1.1 |
| 70 mph | 71.5 mph | +1.5 |
| 90 mph | 91.9 mph | +1.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,214 on the road, so it under-counts by 214. At a true 70 mph the first turns 1024 times a minute, the second 1003.
What drivers reported
225/45R15 carries 2 complaints. Nobody has filed one naming 215/50R15.