355/50R22 vs 345/50R22
Going from one to the other changes the overall height by -1.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 355/50R22 | 345/50R22 | Change |
|---|---|---|---|
| Overall height | 36.0" | 35.6" | -1.1 % |
| Sidewall | 6.99" | 6.79" | -2.8 % |
| Section width | 355 mm | 345 mm | -2.8 % |
| Circumference | 113.0" | 111.8" | -1.1 % |
| Revs per mile | 561 | 567 | +1.1 % |
| Axle height | 17.99" | 17.79" | -5.0 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 355/50R22. Fit 345/50R22 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.7 mph | -0.3 |
| 50 mph | 49.5 mph | -0.5 |
| 70 mph | 69.2 mph | -0.8 |
| 90 mph | 89.0 mph | -1.0 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,891 on the road, so it over-counts by 109. At a true 70 mph the first turns 654 times a minute, the second 661.