345/60R22 vs 355/55R22
Going from one to the other changes the overall height by -2.4 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 345/60R22 | 355/55R22 | Change |
|---|---|---|---|
| Overall height | 38.3" | 37.4" | -2.4 % |
| Sidewall | 8.15" | 7.69" | -5.7 % |
| Section width | 345 mm | 355 mm | +2.9 % |
| Circumference | 120.3" | 117.4" | -2.4 % |
| Revs per mile | 527 | 540 | +2.4 % |
| Axle height | 19.15" | 18.69" | -11.8 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 345/60R22. Fit 355/55R22 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.3 mph | -0.7 |
| 50 mph | 48.8 mph | -1.2 |
| 70 mph | 68.3 mph | -1.7 |
| 90 mph | 87.8 mph | -2.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,758 on the road, so it over-counts by 242. At a true 70 mph the first turns 614 times a minute, the second 630.