285/40R19 vs 275/45R19
Going from one to the other changes the overall height by +2.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 285/40R19 | 275/45R19 | Change |
|---|---|---|---|
| Overall height | 28.0" | 28.7" | +2.7 % |
| Sidewall | 4.49" | 4.87" | +8.6 % |
| Section width | 285 mm | 275 mm | -3.5 % |
| Circumference | 87.9" | 90.3" | +2.7 % |
| Revs per mile | 721 | 702 | -2.7 % |
| Axle height | 13.99" | 14.37" | +9.8 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 285/40R19. Fit 275/45R19 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.8 mph | +0.8 |
| 50 mph | 51.4 mph | +1.4 |
| 70 mph | 71.9 mph | +1.9 |
| 90 mph | 92.5 mph | +2.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,274 on the road, so it under-counts by 274. At a true 70 mph the first turns 841 times a minute, the second 819.
What drivers reported
Nobody has filed a complaint naming 285/40R19. 275/45R19 carries 4.