Tires: Tire Hum, target value, inflation pressure

Question
I am driving a 2007 Honda CRV. I purchased the car new and rotate the tires at each oil change, (5000 miles +/-). The car now has traveled 27500 miles and the tires are beginning to create a vibrational hum at 30 to 55 MPH. They are Continental 4x4 225/65 R 17  102T  M + S. The tires are not showing abnormal wear in the tread from one side or the other across the tire, No evidence of cupping or damage to the sidewall of any tire. Pressure has been maintained as per spec. The tires seem to be worn down to where the Honda tech suggested new tires.  What do you think is happening?

Answer
Roger,

I think you have irregular wear, which is caused by misalignment and aggravated by insufficient inflation pressure and insufficient rotation practices.  While the wear pattern may not be visible, it could still be enough to set off a vibration that comes out in the form of a noise.  So I would get an alignment before you get a new set of tires.

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.