Check your spindle king pins and bearings, we had the same issue a week ago with my Son’s kart
Even though everything was fine on the practice sessions when he did his first race, he came back to the pits with a horrible NEG camber, we patched up the best we could, by maximizing POS camber all the way out, just to compensate for that problem, and just to get him back in the race
But when we brought the kart back to the shop we replaced the spindle bearings and the king pin, sniped it and now it’s ready to go.
The problem you’re having is due to POSITIVE or NEGATIVE camber, depending on where the tire is wearing at ( INSIDE OR OUTSIDE ) Either way, you need to grab the tire while it is still attached to the kart and apply force to it up and down
If you have some amount of movement or significant amount of play, then replace the bearings inside the spindle where the king pin goes, and also replace the king pin, just to be safe. You’d be surprised, ours came out looking like a bottle opener. Lol.