I would not buy a V belt from CT, BB, PA etc. One bad experience is enough. Call an industrial supply place, BDI, Motion, Canada Belting, Canada Bearing...whatever there are tons of them. Its not worth the money saved from with the lower end stuff consumer retail sells.
Why? A good V belt is important to smooth running. A bit of variance in the V width will create vibration and shake - as the wider part goes over a pulley the result is as if the belt tightened. This is an intermittent force, pulling the pulleys together, ends up as vibration