275/70R15 vs 265/75R15
Going from one to the other changes the overall height by +1.6 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/70R15 | 265/75R15 | Change |
|---|---|---|---|
| Overall height | 30.2" | 30.6" | +1.6 % |
| Sidewall | 7.58" | 7.82" | +3.2 % |
| Section width | 275 mm | 265 mm | -3.6 % |
| Circumference | 94.7" | 96.3" | +1.6 % |
| Revs per mile | 669 | 658 | -1.6 % |
| Axle height | 15.08" | 15.32" | +6.3 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 275/70R15. Fit 265/75R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.5 mph | +0.5 |
| 50 mph | 50.8 mph | +0.8 |
| 70 mph | 71.1 mph | +1.1 |
| 90 mph | 91.5 mph | +1.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,163 on the road, so it under-counts by 163. At a true 70 mph the first turns 780 times a minute, the second 768.
What drivers reported
Nobody has filed a complaint naming 275/70R15. 265/75R15 carries 11.