275/35R22 vs 285/30R22
Going from one to the other changes the overall height by -2.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/35R22 | 285/30R22 | Change |
|---|---|---|---|
| Overall height | 29.6" | 28.7" | -2.9 % |
| Sidewall | 3.79" | 3.37" | -11.2 % |
| Section width | 275 mm | 285 mm | +3.6 % |
| Circumference | 92.9" | 90.3" | -2.9 % |
| Revs per mile | 682 | 702 | +2.9 % |
| Axle height | 14.79" | 14.37" | -10.8 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 275/35R22. Fit 285/30R22 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.1 mph | -0.9 |
| 50 mph | 48.6 mph | -1.4 |
| 70 mph | 68.0 mph | -2.0 |
| 90 mph | 87.4 mph | -2.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,714 on the road, so it over-counts by 286. At a true 70 mph the first turns 795 times a minute, the second 819.