We'll be sure to pay particular attention to what you just said about caster. It was so long ago and I don't have the print out so I can't discuss the caster settings I have. If it's not the tires then it would have to be caster that is causing the problem. We were never able to change caster with the previous kit I had, therefore it drove straight with no pull at all. Now that this kit has the ability to adjust caster, that must be the problem I guess. Thanks for discussing those caster settings!