215/70R15 vs 225/70R15
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 | 215/70R15 | 225/70R15 | Change |
|---|---|---|---|
| Overall height | 26.9" | 27.4" | +2.1 % |
| Sidewall | 5.93" | 6.20" | +4.7 % |
| Section width | 215 mm | 225 mm | +4.7 % |
| Circumference | 84.4" | 86.1" | +2.1 % |
| Revs per mile | 751 | 736 | -2.1 % |
| Axle height | 13.43" | 13.70" | +7.0 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 215/70R15. Fit 225/70R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 51.0 mph | +1.0 |
| 70 mph | 71.4 mph | +1.4 |
| 90 mph | 91.8 mph | +1.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,205 on the road, so it under-counts by 205. At a true 70 mph the first turns 876 times a minute, the second 859.