ORIGINAL: davidmil
I talked to API years ago and they recommended changing the chains every 3-5 years depending on usage etc. If you're heavy, maybe more often. I've only replaced mine once in about 10 years. I kept the old pair as a back up. They look great. I'm at the upper end of the weight limit, 250 pounds, when I have all my gear etc up there with me so I too error on the side of caution.
I don't condone going against safety recommendations of the tree stand manufacturer, but they do make $$ when you order replacements from them and also they need to keep their @$$ covered for liability reasons. Also, I understand the chains that API uses are made for combines and can be found in bulk in tractor supply stores. Check out this link for a useful tip on chain covering replacement. I followed it and it works great.
http://www.guncustomizing.com/API-Treestand.htm