I cut the V grooves down to the wheel's steel core for good adhesion. Mine had cracks at both ends of all the spokes and 17 around the rim. Took awhile but looks fine now. The Eastwood Company has PC-7 in small cans for a good price. It's enough to do several wheels. If you have just a few small cracks you can get a dab of the stuff for more money at Chevy Duty.

Never start vast projects with half vast ideas.