265/50R17 vs 285/50R17
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 | 265/50R17 | 285/50R17 | Change |
|---|---|---|---|
| Overall height | 27.4" | 28.2" | +2.9 % |
| Sidewall | 5.22" | 5.61" | +7.5 % |
| Section width | 265 mm | 285 mm | +7.5 % |
| Circumference | 86.2" | 88.7" | +2.9 % |
| Revs per mile | 735 | 715 | -2.9 % |
| Axle height | 13.72" | 14.11" | +10.0 mm |
| Approved rim width | 7.5–9.5" | 8–10.5" | overlap 8–9.5" |
Both are approved on a rim 8" to 9.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 265/50R17. Fit 285/50R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.9 mph | +0.9 |
| 50 mph | 51.4 mph | +1.4 |
| 70 mph | 72.0 mph | +2.0 |
| 90 mph | 92.6 mph | +2.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,287 on the road, so it under-counts by 287. At a true 70 mph the first turns 858 times a minute, the second 834.