335/35R20 vs 315/35R20
Going from one to the other changes the overall height by -1.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 335/35R20 | 315/35R20 | Change |
|---|---|---|---|
| Overall height | 29.2" | 28.7" | -1.9 % |
| Sidewall | 4.62" | 4.34" | -6.0 % |
| Section width | 335 mm | 315 mm | -6.0 % |
| Circumference | 91.8" | 90.1" | -1.9 % |
| Revs per mile | 690 | 703 | +1.9 % |
| Axle height | 14.62" | 14.34" | -7.0 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 335/35R20. Fit 315/35R20 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.4 mph | -0.6 |
| 50 mph | 49.1 mph | -0.9 |
| 70 mph | 68.7 mph | -1.3 |
| 90 mph | 88.3 mph | -1.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,811 on the road, so it over-counts by 189. At a true 70 mph the first turns 805 times a minute, the second 820.
What drivers reported
Nobody has filed a complaint naming 335/35R20. 315/35R20 carries 2.