I have a 6 speed base coupe, bought new 1 yr. ago. (12,000 miles) I'm very well pleased with it.to date. It is equiped with the factory Continental SportContact 2 tires. As of late I notice a deep low pitched "out of round sound" that increases and decreases in conjunction with the change of speed. I've have driven all manner of cars, trucks, motocycles longer than most of you have been a live, and have an ear tuned for things of this nature. My wife of course does not notice it. There is no telegraphed vibration or handling problem of an kind, and upon a quick visual inspection I've found no apparent cause. It seems to disappear at higher speeds. It is very similar to the old "cold thump" sound of nylon cord tires after being parked for a while ( they developed flat spots that eventually went away as they warmed up), but without the telegraphed thump, if any of you remember that. Anyone else notice any thing similar? Any thoughts on the tires being the cause?

My local dealership, where it was purchased has a service dept. staffed with snuff chewing, knuckle draggers, with no credibility what so ever, and of course no Crossfaaaaaaar Tech.

 

I've had that problem with my G35 Coupe, my truck, and many other cars over the years. It's probably your tires. Right at 12,000 miles, my G started the same thing. The wear pattern is so subtle that you wouldn't see it with your eyes, but at speed, you definitely notice it.

 

Just jack it up, and spin the tires with a straight edge a few 16th's of an inch away from the tread. That should show you if or which tire is out of round. Because that's what it sounds like your problem is.
Good Luck

 

After 12k miles maybe it is time to rebalance the tires?

 

yes check your balance but, I drove my '04 70,000 miles and around 15,000 the front all 3 sets of tires started to feel rough ! it wasn't the balance!