265/35R18 vs 285/35R18
Going from one to the other changes the overall height by +2.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 265/35R18 | 285/35R18 | Change |
|---|---|---|---|
| Overall height | 25.3" | 25.9" | +2.2 % |
| Sidewall | 3.65" | 3.93" | +7.5 % |
| Section width | 265 mm | 285 mm | +7.5 % |
| Circumference | 79.5" | 81.2" | +2.2 % |
| Revs per mile | 797 | 780 | -2.2 % |
| Axle height | 12.65" | 12.93" | +7.0 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 265/35R18. Fit 285/35R18 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.7 mph | +0.7 |
| 50 mph | 51.1 mph | +1.1 |
| 70 mph | 71.5 mph | +1.5 |
| 90 mph | 92.0 mph | +2.0 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,218 on the road, so it under-counts by 218. At a true 70 mph the first turns 930 times a minute, the second 910.
What drivers reported
265/35R18 carries 2 complaints. Nobody has filed one naming 285/35R18.