We carry sealed nylon rollers as the standard replacement for steel - they run quieter and don't develop the flat-spot problem that steel rollers get after years of cold-weather cycling. For doors still fitted with 7-ball or 10-ball bearing steel rollers from their original 1970s-80s hardware, we stock the stem lengths that match that era's track spacing, since newer stock rollers don't always fit the older bracket depth without an adapter.
We also keep extended-life rollers with sealed bearings on the truck for anyone who wants to go longer between service calls, which matters more here than in a milder climate given how hard cold cycling is on an unsealed bearing.