425/65R22.5 vs 445/60R22.5
Going from one to the other changes the overall height by -1.6 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 425/65R22.5 | 445/60R22.5 | Change |
|---|---|---|---|
| Overall height | 44.3" | 43.5" | -1.6 % |
| Sidewall | 10.88" | 10.51" | -3.3 % |
| Section width | 425 mm | 445 mm | +4.7 % |
| Circumference | 139.0" | 136.7" | -1.6 % |
| Revs per mile | 456 | 463 | +1.6 % |
| Axle height | 22.13" | 21.76" | -9.3 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 425/65R22.5. Fit 445/60R22.5 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.5 mph | -0.5 |
| 50 mph | 49.2 mph | -0.8 |
| 70 mph | 68.8 mph | -1.2 |
| 90 mph | 88.5 mph | -1.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,835 on the road, so it over-counts by 165. At a true 70 mph the first turns 532 times a minute, the second 541.