It's why you should never buy P21S again...

[Brett Dikeman]

...and its name is WD40.  Thanks to that, the wheels and calipers on
the R are sparkling, and the little dots of tar haven't stopped coming
up; the key is to leave a film of WD40 on the wheel, and that works on
softening up whatever isn't paint.

Afterwards, wash with a strong soap or detergent and wax the wheel.

Also worked wonders on the SS exhaust tips and the rear bumper (you
know the area, where road debris forms a thick layer.)

Brett