355/30R20 vs 335/35R20
Going from one to the other changes the overall height by +3.0 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 355/30R20 | 335/35R20 | Change |
|---|---|---|---|
| Overall height | 28.4" | 29.2" | +3.0 % |
| Sidewall | 4.19" | 4.62" | +10.1 % |
| Section width | 355 mm | 335 mm | -5.6 % |
| Circumference | 89.2" | 91.8" | +3.0 % |
| Revs per mile | 710 | 690 | -3.0 % |
| Axle height | 14.19" | 14.62" | +10.8 mm |
| Approved rim width | 10–13" | 9.5–12.5" | overlap 10–12.5" |
Both are approved on a rim 10" to 12.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 355/30R20. Fit 335/35R20 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.9 mph | +0.9 |
| 50 mph | 51.5 mph | +1.5 |
| 70 mph | 72.1 mph | +2.1 |
| 90 mph | 92.7 mph | +2.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,298 on the road, so it under-counts by 298. At a true 70 mph the first turns 829 times a minute, the second 805.