225/85R22 vs 235/80R22
Going from one to the other changes the overall height by -0.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 225/85R22 | 235/80R22 | Change |
|---|---|---|---|
| Overall height | 37.1" | 36.8" | -0.7 % |
| Sidewall | 7.53" | 7.40" | -1.7 % |
| Section width | 225 mm | 235 mm | +4.4 % |
| Circumference | 116.4" | 115.6" | -0.7 % |
| Revs per mile | 544 | 548 | +0.7 % |
| Axle height | 18.53" | 18.40" | -3.3 mm |
| Approved rim width | 6–8.5" | 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 225/85R22. Fit 235/80R22 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.8 mph | -0.2 |
| 50 mph | 49.7 mph | -0.3 |
| 70 mph | 69.5 mph | -0.5 |
| 90 mph | 89.4 mph | -0.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,931 on the road, so it over-counts by 69. At a true 70 mph the first turns 635 times a minute, the second 639.
What drivers reported
Nobody has filed a complaint naming 225/85R22. 235/80R22 carries 15.