245/65R22 vs 225/75R22
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 | 245/65R22 | 225/75R22 | Change |
|---|---|---|---|
| Overall height | 34.5" | 35.3" | +2.2 % |
| Sidewall | 6.27" | 6.64" | +6.0 % |
| Section width | 245 mm | 225 mm | -8.2 % |
| Circumference | 108.5" | 110.9" | +2.2 % |
| Revs per mile | 584 | 572 | -2.2 % |
| Axle height | 17.27" | 17.64" | +9.5 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 245/65R22. Fit 225/75R22 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 10,217 on the road, so it under-counts by 217. At a true 70 mph the first turns 681 times a minute, the second 667.