Tires: Loud humming - Goodyear RT/S, new brunswick canada, cv joint

Question
Hello--

I have a set of Goodyear RT/S tires on a 2000 Ford Explorer XLT.  They have about 40,000 miles on them and are about 4 years old.  I recently moved from Virginia to New Brunswick, Canada in September and the truck is spending its first winter outdoors in the harsh cold of Canada.

Recently, starting sometime in December, I started noticing that the tires were humming very loudly as I accelerated.  The pitch of the humming increases with increasing speed.  Around 50mph it is at its loudest, and is accompanied by a fast but faint vibration.  Once the truck is up to 70mph (Where I typically hit cruise control), the humming is a bit quiter, but still noticeably louder than usual.  However, when I encounter a bend in the road to the left, the humming decreases a bit.  There is no change in the humming if turned to the right.

I have noticed no difference in the way the truck drives or handles.  The tires still provide the same good traction in snowy or icy conditions.  There is still plenty of tread on all four tires, and to my (admittedly untrained) eye there does not appear to be uneven wear.

The truck was last aligned at the end of August, and does not have a pull to one direction.  I have checked the pressures in the tires and they are all inflated properly.

Could the cold have caused this condition?  Is it a safety issue?  Should I have my truck looked at by a professional?

Thanks for your time.

Answer
Chris,

I suspect you have a CV joint going out, because CV joint noise changes when you turn.   Generally tire noise doesn't or it changes the same whichever way you turn . This is a 4X4 isn't it?

BVut to be sure it isn't a tire - rotate the tires and tire noise will change location.  If it doesn't it's something in the vehicle (or the road.)