245/60R22 vs 225/60R22
Going from one to the other changes the overall height by -2.8 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 245/60R22 | 225/60R22 | Change |
|---|---|---|---|
| Overall height | 33.6" | 32.6" | -2.8 % |
| Sidewall | 5.79" | 5.31" | -8.2 % |
| Section width | 245 mm | 225 mm | -8.2 % |
| Circumference | 105.5" | 102.5" | -2.8 % |
| Revs per mile | 601 | 618 | +2.8 % |
| Axle height | 16.79" | 16.31" | -12.0 mm |
| Approved rim width | 7–9" | 6–8.5" | overlap 7–8.5" |
Both are approved on a rim 7" to 8.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 245/60R22. Fit 225/60R22 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.2 mph | -0.8 |
| 50 mph | 48.6 mph | -1.4 |
| 70 mph | 68.0 mph | -2.0 |
| 90 mph | 87.5 mph | -2.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,719 on the road, so it over-counts by 281. At a true 70 mph the first turns 701 times a minute, the second 721.