235/80R22 vs 235/75R22
Going from one to the other changes the overall height by -2.5 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 235/80R22 | 235/75R22 | Change |
|---|---|---|---|
| Overall height | 36.8" | 35.9" | -2.5 % |
| Sidewall | 7.40" | 6.94" | -6.3 % |
| Section width | 235 mm | 235 mm | 0.0 % |
| Circumference | 115.6" | 112.7" | -2.5 % |
| Revs per mile | 548 | 562 | +2.5 % |
| Axle height | 18.40" | 17.94" | -11.8 mm |
| Approved rim width | 6.5–8.5" | 6.5–8.5" | overlap 6.5–8.5" |
Both are approved on a rim 6.5" 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 235/80R22. Fit 235/75R22 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.2 mph | -0.8 |
| 50 mph | 48.7 mph | -1.3 |
| 70 mph | 68.2 mph | -1.8 |
| 90 mph | 87.7 mph | -2.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,749 on the road, so it over-counts by 251. At a true 70 mph the first turns 639 times a minute, the second 656.
What drivers reported
235/80R22 carries 15 complaints. Nobody has filed one naming 235/75R22.