2011 Toyota Tacoma Vibration in midrange speeds

When accelerating, I feel a noticeable vibration at about 40 mph which is present until about 60 mph. My gas mileage seems to be normal and I don't notice any appreciable loss of power when accelerating (which indicates to me its not a u-joint). I have the original tires which have about 40% tread remaining. I'm wondering if its a wheel bearing or just maybe the tires need to be balanced. Any thoughts? Thanks.