275/80R22.5 vs 285/75R22.5
Going from one to the other changes the overall height by -1.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/80R22.5 | 285/75R22.5 | Change |
|---|---|---|---|
| Overall height | 39.8" | 39.3" | -1.2 % |
| Sidewall | 8.66" | 8.42" | -2.8 % |
| Section width | 275 mm | 285 mm | +3.6 % |
| Circumference | 125.1" | 123.6" | -1.2 % |
| Revs per mile | 506 | 513 | +1.2 % |
| Axle height | 19.91" | 19.67" | -6.3 mm |
| Approved rim width | 7.5–10" | 8–10.5" | overlap 8–10" |
Both are approved on a rim 8" to 10" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 275/80R22.5. Fit 285/75R22.5 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.6 mph | -0.4 |
| 50 mph | 49.4 mph | -0.6 |
| 70 mph | 69.1 mph | -0.9 |
| 90 mph | 88.9 mph | -1.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,876 on the road, so it over-counts by 124. At a true 70 mph the first turns 591 times a minute, the second 598.
What drivers reported
275/80R22.5 carries 2 complaints. Nobody has filed one naming 285/75R22.5.