Went to 20s and need help

[MiCkEy]

I recently upgraded to 20s with TOYO PROXES and AFS wheels. Upgrading to 20s from 17s is the best thing that has happened to the X. Having said that, I have one issue that I am trying to fix and figure the source. Any help will be appreciated:

1. I followed advice and the moment I received the wheels and tires (already mounted and balanced), took them to a balance shop (tire plus). They mounted and rebalanced (Road force setup). The tires according to the guy (who knew what he was doing) were good and rims were not bent or out of round.

2. I put the wheels on (with included hub rings) and everything is hunky dory till a couple of weeks back I started noticing minor vibration/shimmy while driving in the 55-65mph range.

3. I have checked tire pressure, retorqued the lugs but still feeling it.

4. I have searched the acrhives but am lost to where to start now. Would an alignment help? The truck does not pull left or right but I have not had alignment done ever since I purchased the X. My question is, will alignment help in this case.

5. What else can I check without taking it to a stealer? I am guessing perhaps the shimmy was there but not that noticeable because of smaller rims and wheels.

I know its not the rotos and pads as they were changed some 5k-7K miles back. Should I first go with an alignment before checking anything else?

Help ME! Plz.