345/50R24 vs 355/45R24
Going from one to the other changes the overall height by -2.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 345/50R24 | 355/45R24 | Change |
|---|---|---|---|
| Overall height | 37.6" | 36.6" | -2.7 % |
| Sidewall | 6.79" | 6.29" | -7.4 % |
| Section width | 345 mm | 355 mm | +2.9 % |
| Circumference | 118.1" | 114.9" | -2.7 % |
| Revs per mile | 537 | 551 | +2.7 % |
| Axle height | 18.79" | 18.29" | -12.8 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 345/50R24. Fit 355/45R24 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 | 68.1 mph | -1.9 |
| 90 mph | 87.6 mph | -2.4 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,733 on the road, so it over-counts by 267. At a true 70 mph the first turns 626 times a minute, the second 643.