Shimmy at 45 to 55

The dealer has no idea and the service advisor keeps wanting to blame the world.
I took my truck in for rotation and oil change a few weeks ago. Did not have a shimmy in the front till after the rotation. I took the truck back last week after talking to the manager “who I believe is a pretty honest guy” told me it could be one of the tires. He turned me over to one of his advisors who wanted to keep the truck and send it to the company that did the lift and wheels/tires to have them “road force” balance the tires. He had me come back the next day and still have a shimmy. Told me these 35X12.50’s will do this with the offset and size. I called bs and he said it could be the way they were rotated. Bought there new and every service has been there.
Could any of you all maybe she’d some light as to what might be causing this?
Specs
2021 CM
6” ready lift
35x12.50 Toyo A/T’s
Fuel Rampage 2 piece wheels.
24000 on tires.

 

Factory tundra wheels are a high positive offset. Wheels with a negative offset can accentuate small issues.

The entire steering geometry is different with a setup like that. Also tire pressure can and will cause a shimmy this time of year when temperatures vary so much.