Picture This:

The upside-down 'U' side fits over the rim on the side you have 1/2 of the tire mounted on.

Now you have attempted, by hand, to mount the other 1/2 of the tire on the other side of the rim. But there is still, let's say, 6 inches that won't go.

So the other side of the tool straddles the rim and hooks underneath the bead of the tire where you can't get it over the rim.

Now you pull the tool back towards the side that is mounted.

This pulls the bead up and over the rim and seats it.

How's that? Got it?


Looks like the Kool Stop and the VAR work by the same principle. I can vouch for the VAR tool working.