265/45R23 vs 285/45R23
Going from one to the other changes the overall height by +2.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 265/45R23 | 285/45R23 | Change |
|---|---|---|---|
| Overall height | 32.4" | 33.1" | +2.2 % |
| Sidewall | 4.69" | 5.05" | +7.5 % |
| Section width | 265 mm | 285 mm | +7.5 % |
| Circumference | 101.8" | 104.0" | +2.2 % |
| Revs per mile | 623 | 609 | -2.2 % |
| Axle height | 16.19" | 16.55" | +9.0 mm |
| Approved rim width | 7.5–9.5" | 8–10.5" | 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 265/45R23. Fit 285/45R23 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.7 mph | +0.7 |
| 50 mph | 51.1 mph | +1.1 |
| 70 mph | 71.5 mph | +1.5 |
| 90 mph | 92.0 mph | +2.0 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,219 on the road, so it under-counts by 219. At a true 70 mph the first turns 726 times a minute, the second 711.