tires very well could be the problem. How new they are isnt the issue. Some tires hum like crazy, some are quiet. Ride in a car with BFG KD's / KDW's and youll see what I mean.

and yes, dynamat will work, however it is more expensive than other stuff that is essentially the exact same. Its been a long time, but I believe Fatmat is cheaper.

I've personally never been bothered by road noise. I dont like quiet when I drive. Unless its freezing or raining, the windows are open. If not, music is on.

 

A good sound system is usually a better solution to road noise.

 

I have a very good sounds system for the music I listen to (country).

I have a pioneer DEH 4700 headunit and 4 two way speakers with a kenwood amp. It is really amazinf from the upgraded stock speakers which were 20 watt in the front and 25 in the back.

 

I agree that some tires (usually inexpensive) are very noisy. I just spent about $800 on soundproofing materials for my Corolla on an over-zealous audio system upgrade. Fortunately, your 2001 is probably less noisy than my 95. Yes, I am crazy and yes it does help. Unfortunately, it is still not as quiet as a Lexus and there are a few things I would do differently if I had to do it again. There are many things that make a vehicle quiet and soundproofing materials are only part of the equation. I would first recommend buying a Dynamat Extreme bulk pack ($135 off eBay) and apply it to your 4 doors. Sealing the front doors will also improve your speakers sound quality in the mid-bass region. Then decide if that is enough.

 

Also try to get a sound deadening spray to get those hard to reach areas where normal Dynamat applied with a roller cannot reach.