As I mentioned above, tire noises account for more of the wheel bearing-type noises than anything else. A lot of people replace wheel bearings thinking that's where their noise is coming from. But more often than not, it's the tires that make that type of noise. To verify a bad tire(s), rotate the suspected tire to the front or back of its current location. If the noise changes or goes away, you found your bad tire. Replace the tire, preferably as a pair, and recheck for your noise.
It’s not a bad idea to visually inspect your tires for signs of abnormal wear. Run your hand along the top of the tire and feel for rough spots or abnormalities in the tread. If you feel any, it's likely you have an alignment issue, or perhaps some worn or loose suspension parts. It's worth looking into before you get new tires. Also look for bulges in the tire; be sure to check the sidewall as well as the tread. If you find one of these, replace the tire ASAP.
More information on tire issues can be found in the ‘Vibrations’ article.