225/70R19.5 vs 225/75R19.5
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 | 225/70R19.5 | 225/75R19.5 | Change |
|---|---|---|---|
| Overall height | 31.9" | 32.8" | +2.8 % |
| Sidewall | 6.20" | 6.64" | +7.1 % |
| Section width | 225 mm | 225 mm | 0.0 % |
| Circumference | 100.2" | 103.0" | +2.8 % |
| Revs per mile | 632 | 615 | -2.8 % |
| Axle height | 15.95" | 16.39" | +11.3 mm |
| Approved rim width | 6–8.5" | 6–8.5" | overlap 6–8.5" |
Both are approved on a rim 6" 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 225/70R19.5. Fit 225/75R19.5 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 10,278 on the road, so it under-counts by 278. At a true 70 mph the first turns 738 times a minute, the second 718.
What drivers reported
225/70R19.5 carries 20 complaints. Nobody has filed one naming 225/75R19.5.