275/60R19 vs 255/60R19
Going from one to the other changes the overall height by -3.0 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/60R19 | 255/60R19 | Change |
|---|---|---|---|
| Overall height | 32.0" | 31.0" | -3.0 % |
| Sidewall | 6.50" | 6.02" | -7.3 % |
| Section width | 275 mm | 255 mm | -7.3 % |
| Circumference | 100.5" | 97.5" | -3.0 % |
| Revs per mile | 630 | 650 | +3.0 % |
| Axle height | 16.00" | 15.52" | -12.0 mm |
| Approved rim width | 7.5–10" | 7–9.5" | 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 275/60R19. Fit 255/60R19 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.1 mph | -0.9 |
| 50 mph | 48.5 mph | -1.5 |
| 70 mph | 67.9 mph | -2.1 |
| 90 mph | 87.3 mph | -2.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,705 on the road, so it over-counts by 295. At a true 70 mph the first turns 735 times a minute, the second 758.
What drivers reported
Nobody has filed a complaint naming 275/60R19. 255/60R19 carries 9.