345/55R22 vs 355/50R22
Going from one to the other changes the overall height by -2.6 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 345/55R22 | 355/50R22 | Change |
|---|---|---|---|
| Overall height | 36.9" | 36.0" | -2.6 % |
| Sidewall | 7.47" | 6.99" | -6.5 % |
| Section width | 345 mm | 355 mm | +2.9 % |
| Circumference | 116.1" | 113.0" | -2.6 % |
| Revs per mile | 546 | 561 | +2.6 % |
| Axle height | 18.47" | 17.99" | -12.3 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 345/55R22. Fit 355/50R22 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.2 mph | -0.8 |
| 50 mph | 48.7 mph | -1.3 |
| 70 mph | 68.2 mph | -1.8 |
| 90 mph | 87.7 mph | -2.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,739 on the road, so it over-counts by 261. At a true 70 mph the first turns 637 times a minute, the second 654.