I’m not sure what this is, i just tried spraying some Meguairs Ultimate Wheel cleaner on it and it won’t come off. This stuff was on the wheels when I bought the car.

 

Looks like baked on brake dust to me, but may be wrong.

id start with something like p&s brake buster and a soft bristled wheel brush, maybe carpel iron-x if it isn’t brake dust

 

Try tar and sap remover from Stoner Tarminator that get from local autozone.

 

Purple power!
Brought a set of oem 3rd gen 4 runner wheels back from the krustie I got.

 

If you sprayed that wheel when hot the finish has been damaged.

 

Ultimate wheel cleaner is good stuff, so if that didn't get it off then you're gonna have some fun trying to get that off...

See if clay bar will do anything, that would be the next step I would try with it. If that doesn't work, I'd probably guess that the finish is ruined and it'd need to be a wheel that needs to be repainted.

 

The paint on your wheel is permanently damaged. This is what happens when you put Meguiars on a hot wheel. Only way to fix it is to have the wheels refinished or replace them.

Here are a couple threads of the same problem, both used Meguiars on a hot wheel:
https://www.clublexus.com/forums/is-...l-cleaner.html
https://www.clublexus.com/forums/aut...ner-stain.html

 

Thanks for the information everyone! I’m convinced the previous owner must’ve sprayed on the wheels when hot. Guess I’ll just have to get new wheels 😂