335/30R24 vs 315/35R24
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 | 335/30R24 | 315/35R24 | Change |
|---|---|---|---|
| Overall height | 31.9" | 32.7" | +2.4 % |
| Sidewall | 3.96" | 4.34" | +9.7 % |
| Section width | 335 mm | 315 mm | -6.0 % |
| Circumference | 100.3" | 102.7" | +2.4 % |
| Revs per mile | 632 | 617 | -2.4 % |
| Axle height | 15.96" | 16.34" | +9.8 mm |
| Approved rim width | 9.5–12.5" | 8.5–11.5" | overlap 9.5–11.5" |
Both are approved on a rim 9.5" to 11.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 335/30R24. Fit 315/35R24 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 737 times a minute, the second 720.