275/60R18 vs 265/65R18
Going from one to the other changes the overall height by +1.8 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/60R18 | 265/65R18 | Change |
|---|---|---|---|
| Overall height | 31.0" | 31.6" | +1.8 % |
| Sidewall | 6.50" | 6.78" | +4.4 % |
| Section width | 275 mm | 265 mm | -3.6 % |
| Circumference | 97.4" | 99.2" | +1.8 % |
| Revs per mile | 651 | 639 | -1.8 % |
| Axle height | 15.50" | 15.78" | +7.3 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 275/60R18. Fit 265/65R18 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 50.9 mph | +0.9 |
| 70 mph | 71.3 mph | +1.3 |
| 90 mph | 91.7 mph | +1.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,184 on the road, so it under-counts by 184. At a true 70 mph the first turns 759 times a minute, the second 745.
What drivers reported
Nobody has filed a complaint naming 275/60R18. 265/65R18 carries 4.