235/45R19 vs 255/45R19
Going from one to the other changes the overall height by +2.6 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 235/45R19 | 255/45R19 | Change |
|---|---|---|---|
| Overall height | 27.3" | 28.0" | +2.6 % |
| Sidewall | 4.16" | 4.52" | +8.5 % |
| Section width | 235 mm | 255 mm | +8.5 % |
| Circumference | 85.8" | 88.1" | +2.6 % |
| Revs per mile | 738 | 719 | -2.6 % |
| Axle height | 13.66" | 14.02" | +9.0 mm |
| Approved rim width | 6.5–8.5" | 7–9.5" | overlap 7–8.5" |
Both are approved on a rim 7" to 8.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 235/45R19. Fit 255/45R19 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.8 mph | +0.8 |
| 50 mph | 51.3 mph | +1.3 |
| 70 mph | 71.8 mph | +1.8 |
| 90 mph | 92.3 mph | +2.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,259 on the road, so it under-counts by 259. At a true 70 mph the first turns 861 times a minute, the second 839.
What drivers reported
235/45R19 carries 8 complaints. Nobody has filed one naming 255/45R19.