265/60R18 vs 285/55R18
Going from one to the other changes the overall height by -0.6 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 265/60R18 | 285/55R18 | Change |
|---|---|---|---|
| Overall height | 30.5" | 30.3" | -0.6 % |
| Sidewall | 6.26" | 6.17" | -1.4 % |
| Section width | 265 mm | 285 mm | +7.5 % |
| Circumference | 95.9" | 95.3" | -0.6 % |
| Revs per mile | 661 | 665 | +0.6 % |
| Axle height | 15.26" | 15.17" | -2.3 mm |
| Approved rim width | 7.5–9.5" | 8–10.5" | overlap 8–9.5" |
Both are approved on a rim 8" 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 265/60R18. Fit 285/55R18 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.8 mph | -0.2 |
| 50 mph | 49.7 mph | -0.3 |
| 70 mph | 69.6 mph | -0.4 |
| 90 mph | 89.5 mph | -0.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,942 on the road, so it over-counts by 58. At a true 70 mph the first turns 771 times a minute, the second 775.
What drivers reported
265/60R18 carries 19 complaints. Nobody has filed one naming 285/55R18.