Paint spraying in flat Black to the 'tire cave'

[AzChevy86]

Okay, I heard this guy tell me if you spray paint the area behind the tire - ('cave-like') - I don't know what that area is called, but he told me the flat black spray will give the area a depth-look to it. And makes your tire and rims more prominent.... i'm wondering anyone does that to their truck? I seen another truck with its back of tire area all painted black and it looks great!  

[OKUMA111]

IT IS NOT SPRAY PAINT! IT IS RUBBERIZED UNDERCOATING. "TAR". YOU CAN FIND THIS AT ANY AUTOPARTS STORE, WAL-MART, K-MART...ECT AROUND $5.00 EACH CAN.   1 CAN WILL DO 2 FENDER WELLS!