Tires: sudden tire noise, target value, inflation pressure

Question
Just today I noticed that when I drive at speeds over 45mph, the tires seem to be quite loud to the point of being distracting.  The problem is more heard than felt.  When I let go of the steering wheel, it does not pull to one side, so I don't think it's an alignment issue.  I do recall hitting a large pot hole recently, so I'm wondering if they might be out of balance?  I bought 4 new tires in the spring (Turanza w/Serenity), and have only about 7,000 miles on them.  Would you recommend the first course of action being a good wheel balance?  The car is a 2008 Cadillac CTS-4.  Thanks.

Answer
Dan,

There are 3 possibilities.

1)  That the sound isn't tire noise and something else that might sound like tire noise.  In this case you should have someone look at the car - and listen to the noise to determine what it is.

2)  That you have irregular wear.  Irregular wear is caused by misalignment and aggravated by insufficient inflation pressure and insufficient rotation practices.

My experience says that the published alignment tolerances are too wide.  Not the target value, but the allowable deviation from that value.  I think it ought to be half of what is published.

Put another way, the alignment should be within the inner half of the spec.

You should be aware that even vehicles that do not have a pull can be out of alignment.  There are settings where one out of spec condition is offset by another out of spec condition – typically camber vs toe.  

3)  That the tire that encountered the pothole has been damage and that's what's generating the noise.  In this case, you should have a tire shop look at the tire and see if they can detect a problem.