[ACademic]

Billboards are very thin and were only meant for weekend racing and then tossed. That being said, I recall a similar thread on CC a while back that covered proper repairing on these tires (do a search). You are either limited to either a patch or a patch w/inner tube. Just have the tire shop be very careful when they rough-up the interior of the affected patch area with a sanding disc and air grinder...it's considerably thinner than "DOT Approved" tires and easy to go too deep.