Since it's still relatively new (including the tires presumably?) and the DW's are just starting, I would rotate the tires front to back and see if that helps.
Even though in extreme cases you can still feel it in the rear, if it's only one bad tire causing the issue then it should go away as long as that tire stays on the rear axle. If it gets rotated back to the front axle, you'll just get the same symptoms starting over under the same circumstances.
At what point is it starting currently? Just when you get to a certain speed on the same road? Any time? Or somewhere in-between?
Good luck. It's not fun, but it can be fixed.