2001 Cl here with around 80,000 miles.

I've noticed that my car has this loud humming noise at near 55 mph. If I go around 50 or around 60 then nothing is heard. If i go to the automanual and downshift to 4th gear, the sound soften. No lights are llighted up when the humming noise is heard.

Is this normal?

 

Your tires may be cupped.

 

I'd say it's the tires. What kind? Size? How many miles on them?

 

When you down shift, are you decelerating, or staying at the same speed, and down shifting?

 

All Mine:

When i downshift, I remain at the same speed and the sound soften

Niteqwill:

What do you mean by cupped and how do I fix it?

Fuzzy:

They're the normal OEM tires. I think they're michilin and I have had them for around 20,000 miles. I have gotten the tires rotated so don't worry.

I'll look at the tires but I think it is something with the engine. Any ideas?