I just mounted my 20x11x9 holeshots on my quad. It is pulling to one way very bad. Checked psi's and made sure both tires said 20x11x9 on the side. Switched around rear tires and now it pulls the other way. I know its not my front tires because it does it when I'm doing a wheelie too. Never had this problem with stock tires. Please Help

 

Sounds to me like one of the rims is spinning inside of the tire. Whichever direction the quad goes is the side that is spinning. If it goes to the left check the left rear, I'd bust the bead and reseat it. Good luck, hopefully the bead on the tire is not damaged.