In the picture you can see the different measurements on the four different stairs:
4 steps: 835mm * 654mm
3 steps: 625mm * 504mm
2 steps: 415mm * 354mm
1 step: 205mm * 204mm
There are two different types of forks to lower over the fender boom / hammer.
The two types of forks are respectively. 105mm or 140mm in inside width.