Ever since I picked up the STI 4,000 miles ago, I noticed a humming sound from the tires that is loudest at exactly 80MPH. At 90, a 2nd different and quiter humming sound starts up. I took the Service Manager on a test ride and showed him both sounds and he thought they were normal. The 80MPH sound changes when the wheel is turned slightly either way. Then, I put the snow tires (Dunlop Wintersport 3D) and snow wipers on. The 80 MPH sound is now gone. The 90 MPH sound remains, but seems to be coming from the rear now. At somewhere between 90 MPH and 120 MPH, a new, much louder sound has appeared. It doesn't happen all the time, so road surface may have something to do with it, but it has happened on two highways. It is very loud. The only time it happened at a speed as low as 90, was on a very windy day. It is a droneing sort of sound. Usually, to make it happen, you have to go up to 110 or more, but once it starts, slowing down does not make it go away until you drop to 90. I'm thinking it is the side glass on the passenger side bowing outward at speed; made worse by strong crosswinds on that one day where it started at 90). There isn't really a wind leaking sound though. I don't think that window/door fits right. (the door feels like it hangs up and drops 1/4 inch as you open it. The lock looks aligned and the door and glass look aligned though. The Subaru mechanic said it was the trailing edge of the glass sticking to the rubber and he lubricated the rubber. (this new loud sound only started after he did that, but I'm not sure if it started before or after the snows went on since I may not have gone 110 between the lubrication and when the snow tires and wipers went on) One of the reasons I'm thinking glass/door issue instead of tire is that the noise is very inconsistant (it changes a lot at a steady speed; maybe with gusts of wind?) and it doesn't go away or change when you take your foot off the throttle until the speed falls to 90. The easiest thing to try next is to put the regular wipers back on, but I doubt that is it. In the Spring, when the snows come off, it could go away. I could talk to some tire people to see if inspection of the right front tire (where the noise seems to be coming from) could reveal a problem. It looks fine to me. As hard a time as I had to get someone to come on a test drive with me at 80 MPH, I don't think I will ever get anyone to go 110. My biggest concern is just the possibility of a tire or wheel bearing failure at speed, since I don't actually stay at those speeds for very long. The tire wear looks fine on both sets of tires, by the way.

 

Kinda just sounds like tire noise. In my ACR the Paradas were really noisy at lower speeds. At 45 they would suddenly fall silent.
The summer tires on my STI are ALWAYS pretty noisey but the Blizzacks are REALLY noisy up over 65+ on the highway. Around town they are not too bad though. (Thx. for the heads up. I'll be listening intently at 80 and 90 mph. (unless my radar detector beeps..lol)

I doubt your bearings or tires are failing.

 

You know I have had the same thing happen to me somewhere above 110. Exactly that droning noise coming from the rear. I think its just tire noise or something, I talked to my mechanic and thats why he thought. I wouldn't worry about it. What are you doing going 110+ on the highway anyway mister .

 

the only thing I hear @ a 120+ is my turbo sreaming GO FASTER!!!!!

 

yeah i had the same worry....it's probably just the tires, at first i tohught it was a suspension problem, or a bend in my rims, it's just the NVH (noise, vibration, harshness) of some sweet performance tires

 

It might be the noise from the little bit of weather stripping that sticks out at the top of the windows.

Next time you hear the noise try cracking all your windows and rolling them up again.