According to Ryobi, you don't want to pull anything that tips the scales above 1/2 the total weight of the mower plus 1/2 the driver's weight. Ryobi mentions that tongue weight should never exceed ...

One great feature is the mower's built-in rear tow hitch, which allows you to attach a variety of optional accessories, ...

Using an attachment like this Agri-Fab Tow-Behind aerator with your riding mower saves time and greatly reduces the amount of manual labor needed to aerate soil. Your body and lawn will thank you.