After you mount the tire put about 30 psi in it. The work you way around the wheel and use you thumbs to push the tire away from the bead and insure that it is set at the same point on the bead/side wall all the way around. Do this on both sides. It insures the tire is concentric in its location and also that you are not pinching the tube. The pump to full pressure and check again, looking at both sides. Every tire I have ever used has a molding line just above the bead that is good point to use to see if it is mounted in the same place the full 360 on both sides. You may also have a bad tire. That can happen.