Do I need a weight distributing hitch?

i could probably research on the net for this answer but ill exercise your brains: i also have a dually with a 7k dryweight tt. i took it on a trip to kentucky which was about 1900 miles round trip. towed fine, however im just curious what a wd does for the trailer alone. tow vehicle stayed planted entire time. once in a while when caught right, passing a tractor trailer i get sucked in a little. but what does wd do for the trailer itself? i was slightly nose down. it pulled it straight, tested up to about 87ish mph i think i went to. wanted to really test her on an empty stretch of highway i hit. so question: does it make the trailer itself more stable or is it a tow vehicle adjustment they are making?

1. sorry to hijack your thread bud.
2. yes, new to camper world but i drive a tractor trailer for a living.