285/70R18 vs 265/75R18
Going from one to the other changes the overall height by -0.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 285/70R18 | 265/75R18 | Change |
|---|---|---|---|
| Overall height | 33.7" | 33.6" | -0.2 % |
| Sidewall | 7.85" | 7.82" | -0.4 % |
| Section width | 285 mm | 265 mm | -7.0 % |
| Circumference | 105.9" | 105.7" | -0.2 % |
| Revs per mile | 598 | 599 | +0.2 % |
| Axle height | 16.85" | 16.82" | -0.8 mm |
| Approved rim width | 8–10.5" | 7.5–9.5" | 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 285/70R18. Fit 265/75R18 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.9 mph | -0.1 |
| 50 mph | 49.9 mph | -0.1 |
| 70 mph | 69.9 mph | -0.1 |
| 90 mph | 89.8 mph | -0.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,982 on the road, so it over-counts by 18. At a true 70 mph the first turns 698 times a minute, the second 699.
What drivers reported
Nobody has filed a complaint naming 285/70R18. 265/75R18 carries 3.