Don't waste your money on a specific wheel wax - use the same stuff you're using on the rest of the car. The factory wheels on the Limited and Base are clear coated paint, just like the rest of the car. Choose a good quality synthetic sealant like Meguiar's M21 or NXT, Zaino, etc or even just a good carnauba blend. I've been doing this for years on other wheels, including chrome, and it works wonders. Spending money on essentially the same product just for the wheels is not neccessary. I use Meguiar's Quik Wheel Detailer and a microfiber towel after each drive - my car is a weekend toy so it's not like I'm cleaning the wheels daily - and the brake dust comes right off. When the buildup gets bad enough on the inner portion of the wheel, usually around the time I decide to wash the car, I use Meguiar's Wheel Brightener diluted 8:1 with water and it cuts through the worst of it instantly. This product is from Meguiar's Professional Detailer line so yoiu won't find it in autoparts stores, Target, etc, but should be able to find it in paint and body supply stores.

A word of caution about Wheel Brightener though - do NOT use it on chrome wheels as it can stain them, and don't use it full strength or allow it to sit on a hot wheel for a prolonged period. It's very powerful stuff, hence the reason it's sold only in the Pro Detailer line.