I'll bet your pinstripes are looking rough, too...
Turtle Wax hard-shell is a petroleum/silicone-based abrasive wax, and that will tear up vinyl quick. It'* OK for painted/clearcoated rims, but not much else.
If you have vinyl decals and you want them to last, you must use a silicone-free, petroluem-free, abrasive-free, natural wax (such as a pure
carnauba). "Polymer" waxes won't cut it, because they also contain hydrocarbon solvents.
Compared with what you've been using, pure carnauba'* not cheap, you'll be waxing 3 times more often, and it takes 5 times as much elbow grease to get a gloss. AND you have to get every trace
of the old silicone-based wax off first.
Bet the guy who sold you the decals didn't tell you all that, did he
If you want to use a low-cost, durable, easy-shine wax/sealant (or if you'll ever need to use anything even remotely
abrasive, like a swirl remover or a light compound), you'll have to either say goodbye to the vinyl decals, or get your design painted on.