Tires: Noisy Tires, inflation pressure, rear tires

Question
Can tires become noisier at 26k miles vs. 25k miles?

have eagle ls tires on 04 grand prix.  balanced at 25k miles and then took car back to have tires rechecked for balance, flats ect at same location. no flats or or out-of-rounding upon my examination too.  service shop claims tires balance fine.

tires used to be quiet but are quite noisy now?  bad rubber in the LS style?  cords weakening?  (no weather checking in tire face either)

thanks,  

Answer
Al,

What probably happened is that the tire shop did a tire rotation and the noisy rear tires (where you wouldn't notice the noise) are now on the front (where you would notice the noise).

This type of change is usually caused by a misalignment condition, which is aggravated by insufficient inflation pressure and insufficient rotation practices.

So the first step is to get an alignment.