255/60R20 vs 265/55R20
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 | 255/60R20 | 265/55R20 | Change |
|---|---|---|---|
| Overall height | 32.0" | 31.5" | -1.8 % |
| Sidewall | 6.02" | 5.74" | -4.7 % |
| Section width | 255 mm | 265 mm | +3.9 % |
| Circumference | 100.7" | 98.9" | -1.8 % |
| Revs per mile | 629 | 641 | +1.8 % |
| Axle height | 16.02" | 15.74" | -7.3 mm |
| Approved rim width | 7–9.5" | 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 255/60R20. Fit 265/55R20 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 | 68.8 mph | -1.2 |
| 90 mph | 88.4 mph | -1.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,822 on the road, so it over-counts by 178. At a true 70 mph the first turns 734 times a minute, the second 748.
What drivers reported
Nobody has filed a complaint naming 255/60R20. 265/55R20 carries 2.