235/50R22 vs 235/45R22
Going from one to the other changes the overall height by -3.0 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 235/50R22 | 235/45R22 | Change |
|---|---|---|---|
| Overall height | 31.3" | 30.3" | -3.0 % |
| Sidewall | 4.63" | 4.16" | -10.0 % |
| Section width | 235 mm | 235 mm | 0.0 % |
| Circumference | 98.2" | 95.3" | -3.0 % |
| Revs per mile | 645 | 665 | +3.0 % |
| Axle height | 15.63" | 15.16" | -11.8 mm |
| Approved rim width | 6.5–8.5" | 6.5–8.5" | overlap 6.5–8.5" |
Both are approved on a rim 6.5" 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 235/50R22. Fit 235/45R22 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.1 mph | -0.9 |
| 50 mph | 48.5 mph | -1.5 |
| 70 mph | 67.9 mph | -2.1 |
| 90 mph | 87.3 mph | -2.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,704 on the road, so it over-counts by 296. At a true 70 mph the first turns 753 times a minute, the second 776.