Yeah, the clearocat is beginning to peel. Only thing that saves that is to strip the old layer off and apply a new layer. You can try to apply it only in the spots where it's peeling, but you'll need to sand down the areas surrounding the peel and apply a quick shot of clearcoat. << -- *This should only be done once the wheels are thoroughly cleaned and all dirt/grime/brake dust has been removed.
If wheel cleaners aren't doing the job any more, I'd try something like lacquer thinner to see if the dirt/grime comes off. Apply lightly. Do not vigorously scrub it in. If it still doesn't, a wetsand (to remove the etched clearcoat) and then a fresh layer of clear should do the trick.
If the grime DOES come off with lacquer thinner, clean them up the best you can and you may want to spray on a fresh layer of clearcoat. Give them a coat of wax once the clear is dry.
There are several clearcoats you can use. There are ones at the auto stores, but I'd persoanlly recommend 2K Clearcoat:
https://www.amazon.com/dp/B00W2D806Y/?tag=gmtnation-20
It's a 2-part system and will dry rock-solid. You should have all wheels removed, cleaned and ready to be sprayed since this stuff doesn't stay in liquid form for too long once it's activated. There's only a 48 hour window to use it before it dries up inside the spraycan.
*A
good respirator is HIGHLY recommended, and do not spray this stuff near other cars. The mist will fly though the air and it'll stick to just about anything -and dry into tiny water droplet looking thingies.