215/50R14 vs 225/45R14
Going from one to the other changes the overall height by -2.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/50R14 | 225/45R14 | Change |
|---|---|---|---|
| Overall height | 22.5" | 22.0" | -2.2 % |
| Sidewall | 4.23" | 3.99" | -5.8 % |
| Section width | 215 mm | 225 mm | +4.7 % |
| Circumference | 70.6" | 69.0" | -2.2 % |
| Revs per mile | 898 | 918 | +2.2 % |
| Axle height | 11.23" | 10.99" | -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 215/50R14. Fit 225/45R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.3 mph | -0.7 |
| 50 mph | 48.9 mph | -1.1 |
| 70 mph | 68.5 mph | -1.5 |
| 90 mph | 88.0 mph | -2.0 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,781 on the road, so it over-counts by 219. At a true 70 mph the first turns 1047 times a minute, the second 1071.