225/70R22 vs 225/75R22
Going from one to the other changes the overall height by +2.6 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 225/70R22 | 225/75R22 | Change |
|---|---|---|---|
| Overall height | 34.4" | 35.3" | +2.6 % |
| Sidewall | 6.20" | 6.64" | +7.1 % |
| Section width | 225 mm | 225 mm | 0.0 % |
| Circumference | 108.1" | 110.9" | +2.6 % |
| Revs per mile | 586 | 572 | -2.6 % |
| Axle height | 17.20" | 17.64" | +11.3 mm |
| Approved rim width | 6–8.5" | 6–8.5" | overlap 6–8.5" |
Both are approved on a rim 6" 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 225/70R22. Fit 225/75R22 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.8 mph | +0.8 |
| 50 mph | 51.3 mph | +1.3 |
| 70 mph | 71.8 mph | +1.8 |
| 90 mph | 92.3 mph | +2.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,257 on the road, so it under-counts by 257. At a true 70 mph the first turns 684 times a minute, the second 667.