Worn out leaf springs can definitely cause a trailer to sag like you described in your question, which leads to a variety of issues such as reduced wheel well clearance for the tires. If you measured a length of 25-1/2" from eye to eye (on center) with weight taken off the trailer, the 4-Leaf Double-Eye Spring # e54SR will work great as a replacement.
Older leaf springs will have stretched out over time, so the shorter 25-1/8" length on these new springs should be the correct fit on your... view full answer...