I have a noise coming from my tire when I reach 40-45 MPH, what could it be?

I changed the tire thinking that it would go away, I have a 2008 Toyota Yaris, my alignment doesn't seem to be off, when I reach 40-45 mph I begin hearing a whirring sound coming from the drivers side front tire. Hard to explain but it isn't on-going. (vuum..vuum..vuum..vuum) If I go faster or slower it goes away. I thought it was a bearing but the Auto Tech at Bell Tire said that my bearings look fine, I do need to replace a tire on my car but the noise doesn't seem to be origination from there. Any help would be greatly appreciated, I'm afraid to drive on the highway because I've been doing research on things that could happen while you're driving with bad bearings and it isn't pretty.