Had the same issue when I traded in my TT for a new one in February. Checked for them in all the local hardware stores in the area and Tractor Supply. Nobody had anything heavy enough. They suggested I go to a local trailer dealer (they build and sell utility trailers not TTs). They only had 1 and I needed 4. So I had to wait until their supply truck came in the next day. The salesperson wanted to sell me exactly what I had since I took one in as an example, but I knew I needed longer ones.