Customer (name blocked for privacy);

two likely possibilities:

(1) A worn (cupped) tire, making noise from the flat spots hitting the road surface at high speed. Feel the tread area of the tire; if it feels worn or uneven, it may be the source of the noise. Try rotating it to another position on the car to see if the noise moves with it.

(2) A failing wheel bearing. Wheel bearings make a loud rumbling/ roaring moise when they are worn out. Often, if only one wheel bearing is bad, it will change in volume when turning at highway speeds. Drive at a speed wheere you hear the noise, then turn the stering wheel gently back and forth to shift the weight of the car from side to side. If the noise gets louder and quieter depending on direction, then a failing wheel bearing is the cause. The bad bearing will be on the outside of the turn direction when the noise is loudest, because the vehicle's weight is shifted more onto the outside bearing when turning.

I hope this is helpful; if so, an accept would be most appreciated! Thanks!