It's actually not fading, the design is a series of little dots that get further spaced out as you move towards the back of the car, thus "fading" into the body color. It is, however, starting to flake off in certain places. When I bought the car, I though for sure it would be the first thing to come off, but lately I've been debating whether or not to get rid of it, cuz I kinda like it now that the wheels are white.
Mine: 2006 Mazda3 s GT Hatch: 115k, Gray, Manual
Gone: 2002 SVT, #1654
Hers: 2012 Focus Ti Sedan: 55k, SGM, Manual