People have this issue with bone stock vehicles and OEM tire sizes on tight front ends? I've come from a lifted Jeep so I do know a fair bit about front end vibes through the wheel and where they typically originate, I'm sure many of us here do but in the Jeep world at least ( and my good buddy makes his living on modifying them specifically ) they don't just come on all of a sudden or come and go, there is always a common denominator even if its simple tire wear, belt shifts which are really hard to diagnose.
We tossed u-joints and stabilizers at my last truck to try and calm a minor vibe at highway speeds to no avail, turns out a simple decrease in the transfer case drop kit did the trick ( which is usually the opposite problem - you need more )
I know our front ends are significantly more complicated then the front end of a Jeep which has half the alignment consideration too but I have a hard time understanding these issues crop up on bone stock vehicles. I hope - I only have 1500 miles on our TRD OR right now but drive frequently at these suspected speeds and everything rolls along as smooth as butter.
I don't expect these Duellers to last too long, so I'll be very picky on replacements - the Duratracs on my last Jeep started to have vibe issues and required frequent rotations to keep their belts wearing properly I thought. They sure got loud as hell around the 50K mark which was annoying.