Slick reading

with that weight and itty bitty tire I would start at 12psi. if the hotrod is stable at speed, not wondering side to side, I would lower the it 1psi at a time until it started to wonder then go back up the 1psi. that will be the correct pressure. the wavy pattern is just the normal wear. not going all the way across means there is too much pressure or the rim is too narrow. a 10.5" slick should be on a 9"-11" rim, some folds like a 12" rim.