I've noticed a chirping noise coming from the front driver's side wheel

For about 6 months I've noticed a chirping noise coming from the front driver's side wheel. It's not loud, but very noticeable when you have the windows down. I mainly notice it coasting about 20-30 mph, or going through quiet parking lots. The chirping gets faster as the truck goes faster. It almost sounds like one part of the wheel rubs against something every time there is a full revolution. The squeak is comparable to what a cricket sounds like. I thought it was the brakes because the noise stops when I gently apply the brakes, but I had a brake inspection and they said the brakes were only about 1/2 worn. The noise also seems to stop when I turn to the right. Any ideas?