Silverado 2017 LTZ shake in front end

[canucktravellers]

New Poster here...

Just wondering if anyone on here has had this issue with their recent Silverado?
This Truck is a 2017, LTZ, 6.2 Liter, 8 speed, 19,000 Miles. Bought in October, 2016 so vehicle is 25 months old.
We just came down from Canada without the Trailer, 2100 Miles (3380Kms) and experienced a shake in the steering wheel at various speeds usually at certain specific speeds like 56 Mph and under slight load like on a hill or just accelerating, a few more MPH and it stops. Now that we are here in Florida I find it does this at certain lower speeds like 40 MPH raise it to 45 and it stops.

It appears to be in the front end as I can feel it through the steering wheel. I had to before leaving Canada get a new Goodyear Tire due to a nail in the wall of the existing front right wheel, the tires were rotated and this new tire was placed on the left rear of the vehicle. Not much wear on any of the existing tires so all the existing tires depth is close to the new tire.
The tires are Goodyear Eagle LS-2 275/55R20

I was curious if anyone had this experience, I am going to get an appointment with the local Chevy dealer, I am thinking he might balance the tires and if that does not stop it maybe it's in the running mechanism. There is some discussion on the Tranny in these vehicles and I experience it also like aggressive shifting and noisy thuds (sometimes, not all the times) I have had several dealers look into this with the no trouble found response.
Thinking it could be tires, maybe broken hidden belts, unbalanced tires, or a problem in the running gear, Tranny, etc.
Appreciate any experience others may have had in regards to this issue, thanks....Ernie