Try installing a marathon on a 16" rim :-(

It is easier after they've been on the rim, though. But I carry a "bead jack" with me just in case.

This one is the easiest to find:


It's the Koolstop bead jack from Amazon.

The VAR tire lever is a bead jack that is more portable than the Koolstop one, but it can be harder find in the US: