I recently found out there's some dirt stick on painted area of my car's rear wheel.. Anyone knows how to get those off? the dirt looks kinda brownish... I've tried mother clay bar and something called compound...both wouldn't do the job... plz help

Cheers,
Verra

Does it look like little dots of rust? If so, it probably is from metallic particles that landed on the paint and rusted. In this case, it's almost impossible to remove them.

If it's just an overall brownish/dirty appearance on the wheel, you can try paint cleaner (like Meguiar's Step 1 - Paint Cleaner) to clean it off. This may also help lessen the above mentioned rust dots, if that's what it is.

elbow grease though.