265/40R17 vs 285/40R17
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 | 265/40R17 | 285/40R17 | Change |
|---|---|---|---|
| Overall height | 25.3" | 26.0" | +2.5 % |
| Sidewall | 4.17" | 4.49" | +7.5 % |
| Section width | 265 mm | 285 mm | +7.5 % |
| Circumference | 79.6" | 81.6" | +2.5 % |
| Revs per mile | 796 | 776 | -2.5 % |
| Axle height | 12.67" | 12.99" | +8.0 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 265/40R17. Fit 285/40R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.7 mph | +0.7 |
| 50 mph | 51.2 mph | +1.2 |
| 70 mph | 71.7 mph | +1.7 |
| 90 mph | 92.2 mph | +2.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,249 on the road, so it under-counts by 249. At a true 70 mph the first turns 928 times a minute, the second 906.
What drivers reported
265/40R17 carries 1 complaints. Nobody has filed one naming 285/40R17.