235/70R19 vs 255/60R19
Going from one to the other changes the overall height by -2.8 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 235/70R19 | 255/60R19 | Change |
|---|---|---|---|
| Overall height | 32.0" | 31.0" | -2.8 % |
| Sidewall | 6.48" | 6.02" | -7.0 % |
| Section width | 235 mm | 255 mm | +8.5 % |
| Circumference | 100.4" | 97.5" | -2.8 % |
| Revs per mile | 631 | 650 | +2.8 % |
| Axle height | 15.98" | 15.52" | -11.5 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 235/70R19. 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 | 48.6 mph | -1.4 |
| 70 mph | 68.0 mph | -2.0 |
| 90 mph | 87.4 mph | -2.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,717 on the road, so it over-counts by 283. At a true 70 mph the first turns 736 times a minute, the second 758.
What drivers reported
Nobody has filed a complaint naming 235/70R19. 255/60R19 carries 9.