335/50R20 vs 355/45R20
Going from one to the other changes the overall height by -1.8 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 335/50R20 | 355/45R20 | Change |
|---|---|---|---|
| Overall height | 33.2" | 32.6" | -1.8 % |
| Sidewall | 6.59" | 6.29" | -4.6 % |
| Section width | 335 mm | 355 mm | +6.0 % |
| Circumference | 104.3" | 102.3" | -1.8 % |
| Revs per mile | 608 | 619 | +1.8 % |
| Axle height | 16.59" | 16.29" | -7.8 mm |
| Approved rim width | 9.5–12.5" | 10–13" | 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 335/50R20. Fit 355/45R20 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 9,816 on the road, so it over-counts by 184. At a true 70 mph the first turns 709 times a minute, the second 722.