285/35R22 vs 265/40R22
Going from one to the other changes the overall height by +1.6 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 285/35R22 | 265/40R22 | Change |
|---|---|---|---|
| Overall height | 29.9" | 30.3" | +1.6 % |
| Sidewall | 3.93" | 4.17" | +6.3 % |
| Section width | 285 mm | 265 mm | -7.0 % |
| Circumference | 93.8" | 95.3" | +1.6 % |
| Revs per mile | 676 | 665 | -1.6 % |
| Axle height | 14.93" | 15.17" | +6.3 mm |
| Approved rim width | 8–10.5" | 7.5–9.5" | overlap 8–9.5" |
Both are approved on a rim 8" to 9.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 285/35R22. Fit 265/40R22 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.5 mph | +0.5 |
| 50 mph | 50.8 mph | +0.8 |
| 70 mph | 71.2 mph | +1.2 |
| 90 mph | 91.5 mph | +1.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,165 on the road, so it under-counts by 165. At a true 70 mph the first turns 788 times a minute, the second 775.