275/55R18 vs 265/60R18
Going from one to the other changes the overall height by +2.0 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/55R18 | 265/60R18 | Change |
|---|---|---|---|
| Overall height | 29.9" | 30.5" | +2.0 % |
| Sidewall | 5.95" | 6.26" | +5.1 % |
| Section width | 275 mm | 265 mm | -3.6 % |
| Circumference | 94.0" | 95.9" | +2.0 % |
| Revs per mile | 674 | 661 | -2.0 % |
| Axle height | 14.95" | 15.26" | +7.8 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 275/55R18. Fit 265/60R18 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 51.0 mph | +1.0 |
| 70 mph | 71.4 mph | +1.4 |
| 90 mph | 91.8 mph | +1.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,204 on the road, so it under-counts by 204. At a true 70 mph the first turns 787 times a minute, the second 771.
What drivers reported
Nobody has filed a complaint naming 275/55R18. 265/60R18 carries 19.