Yearly trailer maintenance for me includes new bearings and brake pads needed or not. Hub turning if necessary and an in-depth inspection of the calipers. I also tune or replace anything else that may need some love. My boat and trailer are old, born in 2006. My trailer torsion "arms" are cast (correct me if I'm wrong) and rust like hell. Each year I chip the rust off and spay with oil. They still rust and each year i chip a little off, but this year holly crap. When are these not safe anymore? Anyone have any knowledge around this subject?