265/65R18 vs 275/60R18
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 | 265/65R18 | 275/60R18 | Change |
|---|---|---|---|
| Overall height | 31.6" | 31.0" | -1.8 % |
| Sidewall | 6.78" | 6.50" | -4.2 % |
| Section width | 265 mm | 275 mm | +3.8 % |
| Circumference | 99.2" | 97.4" | -1.8 % |
| Revs per mile | 639 | 651 | +1.8 % |
| Axle height | 15.78" | 15.50" | -7.3 mm |
| Approved rim width | 7.5–9.5" | 7.5–10" | 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 265/65R18. Fit 275/60R18 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 | 68.7 mph | -1.3 |
| 90 mph | 88.4 mph | -1.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,819 on the road, so it over-counts by 181. At a true 70 mph the first turns 745 times a minute, the second 759.
What drivers reported
265/65R18 carries 4 complaints. Nobody has filed one naming 275/60R18.