Here are some things that I have run into similar to your description: Your description of a "humming" sound does not seem to indicate a problem with a bent rim or misalignment. If it were a bent rim, you should experience a vibration and not just a noise. If this humming started after you had 7,000 miles on the tires, then the only possible tire related thing to check is for some type of visible irregular wear on the tires that might cause a noise, like a cupping or feathering of the tread elements. If you do have some unusual kind of wear, then you will also need to troubleshoot the suspension to find out why you have this irregular wear. Are you rinding on a newly re-paved roads? in some cases, driving on newly paved roads can result in some pretty loud noises from some tires. Good Luck.