275/55R16 vs 285/50R16
Going from one to the other changes the overall height by -2.5 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/55R16 | 285/50R16 | Change |
|---|---|---|---|
| Overall height | 27.9" | 27.2" | -2.5 % |
| Sidewall | 5.95" | 5.61" | -5.8 % |
| Section width | 275 mm | 285 mm | +3.6 % |
| Circumference | 87.7" | 85.5" | -2.5 % |
| Revs per mile | 723 | 741 | +2.5 % |
| Axle height | 13.95" | 13.61" | -8.8 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 275/55R16. Fit 285/50R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.3 mph | -0.7 |
| 50 mph | 48.8 mph | -1.2 |
| 70 mph | 68.3 mph | -1.7 |
| 90 mph | 87.8 mph | -2.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,753 on the road, so it over-counts by 247. At a true 70 mph the first turns 843 times a minute, the second 864.