275/65R17 vs 265/70R17
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 | 275/65R17 | 265/70R17 | Change |
|---|---|---|---|
| Overall height | 31.1" | 31.6" | +1.7 % |
| Sidewall | 7.04" | 7.30" | +3.8 % |
| Section width | 275 mm | 265 mm | -3.6 % |
| Circumference | 97.6" | 99.3" | +1.7 % |
| Revs per mile | 649 | 638 | -1.7 % |
| Axle height | 15.54" | 15.80" | +6.8 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 275/65R17. Fit 265/70R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.5 mph | +0.5 |
| 50 mph | 50.9 mph | +0.9 |
| 70 mph | 71.2 mph | +1.2 |
| 90 mph | 91.5 mph | +1.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,171 on the road, so it under-counts by 171. At a true 70 mph the first turns 757 times a minute, the second 744.