325/35R24 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 | 325/35R24 | 305/35R24 | Change |
|---|---|---|---|
| Overall height | 33.0" | 32.4" | -1.7 % |
| Sidewall | 4.48" | 4.20" | -6.2 % |
| Section width | 325 mm | 305 mm | -6.2 % |
| Circumference | 103.5" | 101.8" | -1.7 % |
| Revs per mile | 612 | 622 | +1.7 % |
| Axle height | 16.48" | 16.20" | -7.0 mm |
| Approved rim width | 9–12" | 8.5–11" | overlap 9–11" |
Both are approved on a rim 9" to 11" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 325/35R24. Fit 305/35R24 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.5 mph | -0.5 |
| 50 mph | 49.2 mph | -0.8 |
| 70 mph | 68.8 mph | -1.2 |
| 90 mph | 88.5 mph | -1.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,833 on the road, so it over-counts by 167. At a true 70 mph the first turns 714 times a minute, the second 726.
What drivers reported
Nobody has filed a complaint naming 325/35R24. 305/35R24 carries 1.