285/35R24 vs 305/35R24
Going from one to the other changes the overall height by +1.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 285/35R24 | 305/35R24 | Change |
|---|---|---|---|
| Overall height | 31.9" | 32.4" | +1.7 % |
| Sidewall | 3.93" | 4.20" | +7.0 % |
| Section width | 285 mm | 305 mm | +7.0 % |
| Circumference | 100.1" | 101.8" | +1.7 % |
| Revs per mile | 633 | 622 | -1.7 % |
| Axle height | 15.93" | 16.20" | +7.0 mm |
| Approved rim width | 8–10.5" | 8.5–11" | overlap 8.5–10.5" |
Both are approved on a rim 8.5" to 10.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 285/35R24. Fit 305/35R24 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.5 mph | +0.5 |
| 50 mph | 50.9 mph | +0.9 |
| 70 mph | 71.2 mph | +1.2 |
| 90 mph | 91.6 mph | +1.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,173 on the road, so it under-counts by 173. At a true 70 mph the first turns 739 times a minute, the second 726.
What drivers reported
Nobody has filed a complaint naming 285/35R24. 305/35R24 carries 1.