285/55R24 vs 275/60R24
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 | 285/55R24 | 275/60R24 | Change |
|---|---|---|---|
| Overall height | 36.3" | 37.0" | +1.8 % |
| Sidewall | 6.17" | 6.50" | +5.3 % |
| Section width | 285 mm | 275 mm | -3.5 % |
| Circumference | 114.2" | 116.2" | +1.8 % |
| Revs per mile | 555 | 545 | -1.8 % |
| Axle height | 18.17" | 18.50" | +8.3 mm |
| Approved rim width | 8–10.5" | 7.5–10" | overlap 8–10" |
Both are approved on a rim 8" to 10" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 285/55R24. Fit 275/60R24 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 | 71.3 mph | +1.3 |
| 90 mph | 91.6 mph | +1.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,179 on the road, so it under-counts by 179. At a true 70 mph the first turns 647 times a minute, the second 636.