How to choose correct Leaf spring rating?

The previous owner had multiple bearing failures on the 3500 axles and ruined the spindles so I needed 2. The trailer store said to go 5200 for bigger bearings and brakes. Price was negligible something like less than $40 per axle over the 4400 which is essensially a 3500 with only a slightly bigger outter bearing and a 3" tube instead of a 2-3/8". The 5200 bearings are HUGE in comparison!! (Old one right, new one left). IMO you can't have too big of a bearing and the 12" brakes over the 10" ought to be a worthy improvement too.





Anyway I'm going to tell the guy I want the 2400lb springs then