Noise like maybe a hum starting at about 10-15 mph that increasingly gets louder the faster you go...what could it be?

I think maybe its the tires, lift both of the cars front tires off the ground start the car and put into drive hit the gas and see if the sound is still there.

A humming noise that changes with speed indicative of a wheel bearing noise. Joemom had a good idea on how to check that. If in fact it is the wheel bearing making noise I suggest that you replace both at the same time. One may be making noise now but most likely they are both making noise except one is louder than the other. Too many times a customer has requested replacement of just one and come back a few days later to replace the other side.