why are you going 85mph when the car is cold
I suspect what you are experiencing is tire flat spotting. for the first couple of miles the tires will not roll perfectly round. increasing tire pressure decreases this tendency to flat spot.
it happens on tires with relatively soft sidewalls, most notoriously continental dws and other rayon-belted tires. however, I have experienced it slightly on my Michelin PS2 after having the car sit for a few days.