I would not use stainless filler to weld it. Most rods are alloy steel with a thin chrome plating on them. Use something like 70-S6 for filler. I normally mig weld cylinders and rods when I build/modify them.
I cut my chains to fit like many have posted, align on tires, then I made my own tensioner out of short chains with hooks on the ends and threaded rod through the center of each chain. Zoom in on tire. My chains stay tight for months, long winters in maine. Easy and cheap to make/use.