275/75R18 vs 265/75R18
Going from one to the other changes the overall height by -1.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/75R18 | 265/75R18 | Change |
|---|---|---|---|
| Overall height | 34.2" | 33.6" | -1.7 % |
| Sidewall | 8.12" | 7.82" | -3.6 % |
| Section width | 275 mm | 265 mm | -3.6 % |
| Circumference | 107.6" | 105.7" | -1.7 % |
| Revs per mile | 589 | 599 | +1.7 % |
| Axle height | 17.12" | 16.82" | -7.5 mm |
| Approved rim width | 7.5–10" | 7.5–9.5" | overlap 7.5–9.5" |
Both are approved on a rim 7.5" 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 275/75R18. Fit 265/75R18 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.5 mph | -0.5 |
| 50 mph | 49.1 mph | -0.9 |
| 70 mph | 68.8 mph | -1.2 |
| 90 mph | 88.4 mph | -1.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,828 on the road, so it over-counts by 172. At a true 70 mph the first turns 687 times a minute, the second 699.
What drivers reported
Nobody has filed a complaint naming 275/75R18. 265/75R18 carries 3.