Front end vibration...sometimes.

To start, 35,500 miles on my '17 stock Limited, zero off road, and very little towing. I know that warped rotors result in a steering wheel vibration when the brakes are applied and my experience in an '05 Highlander that once warped, the wheel vibrated every time the brakes were applied. Any thoughts on why my steering wheel only shakes sometimes when the brakes are applied? It's usually at highway speed >55 MPH, but not always which is the strange part.
I'm hoping that I don't have to go for rotors as I know that they probably won't be covered by my warranty that expires real soon. Taking it in tomorrow AM for the dealer's opinion. Y'all's thoughts appreciated. Suspension issue perhaps? (I hope.)
Thanks in advance!

 

idk mine has always been shaky a bit. I just upgraded to 5100s with 888s and alot of the shakiness seems to have gone away.
especially during slow down.

 

probably warped rotors, will happen more often at higher speed and when the brakes warmed up.

 

Without knowing all the variables, like trailer brakes, how heavy, etc, etc-
Since you mentioned towing, I'm leaning towards warped rotors, measure them. It only takes one overheat situation to warp them.

 

Hey - That guy here.... Rotors DO NOT physically warp. Its just uneven pad deposits. Not easily measured per se, but should be visible on a brake lathe.

You could simply go out and do a bedding procedure on your existing setup to try and smooth it out a bit, or have the rotors resurfaced and add some new pads. (then bed those properly)

Also verify the calipers are in good working order with no seized or binding parts - you are probably over due for a brake fluid flush if you have never done so.