285/30R17 vs 265/35R17
Going from one to the other changes the overall height by +2.4 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 285/30R17 | 265/35R17 | Change |
|---|---|---|---|
| Overall height | 23.7" | 24.3" | +2.4 % |
| Sidewall | 3.37" | 3.65" | +8.5 % |
| Section width | 285 mm | 265 mm | -7.0 % |
| Circumference | 74.6" | 76.4" | +2.4 % |
| Revs per mile | 850 | 830 | -2.4 % |
| Axle height | 11.87" | 12.15" | +7.3 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 285/30R17. Fit 265/35R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.7 mph | +0.7 |
| 50 mph | 51.2 mph | +1.2 |
| 70 mph | 71.7 mph | +1.7 |
| 90 mph | 92.2 mph | +2.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,241 on the road, so it under-counts by 241. At a true 70 mph the first turns 991 times a minute, the second 968.