425/60R22.5 vs 445/55R22.5
Going from one to the other changes the overall height by -1.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 425/60R22.5 | 445/55R22.5 | Change |
|---|---|---|---|
| Overall height | 42.6" | 41.8" | -1.9 % |
| Sidewall | 10.04" | 9.64" | -4.0 % |
| Section width | 425 mm | 445 mm | +4.7 % |
| Circumference | 133.8" | 131.2" | -1.9 % |
| Revs per mile | 474 | 483 | +1.9 % |
| Axle height | 21.29" | 20.89" | -10.3 mm |
| Approved rim width | 12–15" | 13–16" | overlap 13–15" |
Both are approved on a rim 13" to 15" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 425/60R22.5. Fit 445/55R22.5 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.4 mph | -0.6 |
| 50 mph | 49.1 mph | -0.9 |
| 70 mph | 68.7 mph | -1.3 |
| 90 mph | 88.3 mph | -1.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,810 on the road, so it over-counts by 190. At a true 70 mph the first turns 553 times a minute, the second 563.