Ok, I've got a set of BFGoodrich Radial T/A's on my Mystique, and I started to notice a little darkening of the letters on the tires. I clean them regularly, and all the whitewall itself is still on(not rubbed off at all), just not blindingly white like I want them to be. Can I just bleach the letters with like a Clorox bleach pen, or is there an easier, more blackwall-friendly approach. Thanks in advance.