I keep getting this low noise from the RF wheel location, I havent been able to figure it out, its been happening since I stopped using the smaller tires wide w/ treads they were costing $350 a piece & my bank acct cannot support it, its not the getto wheelbaro tire(I went thru 2 sets of them cause im heavy on the throttle). Anyways the noise starts at 51-52 mph and on up to 85mph, but if I slow down to 50mph it goes away.

I thought at first a front end alingment was needed but that didnt help, even with adjustable caster bolts the noise wont go away, its very annoying, I'd rather listen to my exhaust cutout with the windows up. I've checked the brakes, lugs for tightness and the rest suspension but nothing shows up. I just rolled over 100K miles on the clock, and I geuss its time for bearings. It just has me wondering why only one side makes this noise and not the other.

'98XLT F150 5.4L St. Cab 2wd

 

I too have this issue and have been told it's due to tire cupping. Apparently it is due to non rotation of the tires in a timely fashion. Whats timely you ask? The service tech at ford told me every 10,000 km (not sure what that is in miles). That seems a little too frequent for my liking. Hope this helped

 

I just rotated my tires and that didnt help one bit, it actually made it worse, now it starts this noise at 35 instead of 50-52. I can rock my wheeels back and forth indicating new bearings are needed, my rotors eating pads like crazy the brake dust is very heavy and Im getting more pissed every day that this happens, not only that but the truck grabs really hard if you apply the brakes lightly and sometimes it squeals to a stop...........very annoying.

 

I had a similar problem that started about a month ago... The truck was making an audible and slightly annoying whirring sound that was only noticible at 49-52 mph and seemed to come from the left rear tire. Since the truck is still under factory warranty, I took it in to the dealership, and they ended up rebuilding the entire rear-end. apparently it was the ring and pinion making the sound. Glad I brought it in when I did. They didn't tell me much else so I don't know if the case was empty or what... dunno if this helps but I thought I'd throw it out there.

Don