Bicycle Trailer pulls back wheel sideways I have 2 bikes. A touring bike and a mountain bike. The touring bike pulls my 40 lb daughter, snacks, and water just fine (with a Burley classic hitch). The mountain bike on the other hand pulls for about a mile then the front of the tire starts to cant to the right, eventually rubbing on the frame. This used to happen on my old univega mountain bike when pulling my son. 
Anyone have any ideas on how to fix this or why it is happening? Is it because my touring bike is designed to pull a heavier load? Thanks in advance!
It is possible that you put not enough torque on axle nuts. The axle moves in the fork.
 If there is enough space, add some extra, broad spacers and then screw it back to the frame.

Use this kind of spacer (it's from Sram I-3, might require some drilling)