275/35R17 vs 285/35R17
Going from one to the other changes the overall height by +1.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/35R17 | 285/35R17 | Change |
|---|---|---|---|
| Overall height | 24.6" | 24.9" | +1.1 % |
| Sidewall | 3.79" | 3.93" | +3.6 % |
| Section width | 275 mm | 285 mm | +3.6 % |
| Circumference | 77.2" | 78.1" | +1.1 % |
| Revs per mile | 821 | 811 | -1.1 % |
| Axle height | 12.29" | 12.43" | +3.5 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 275/35R17. Fit 285/35R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.3 mph | +0.3 |
| 50 mph | 50.6 mph | +0.6 |
| 70 mph | 70.8 mph | +0.8 |
| 90 mph | 91.0 mph | +1.0 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,112 on the road, so it under-counts by 112. At a true 70 mph the first turns 957 times a minute, the second 947.