I have a set of 16" rims off a 99 and want to know how to make them fit on my 06 350 with the bigger rotors ? Do they make spacers to put behind the rims ?

Hubcentric wheel spacers. Done it before to clear 16.5"s

Great .. How thick did you have to go ? ..Thanks

You'll have to go a minimum of 2" just to clear the studs themselves. If you dont mind cutting the stock studs, you might could get away with less, but I really dont know.

Keep in mind most rims meant for 99-04 have 1" less backspacing than the 05-present wheels. This means even wider.

The 2" spacers are $300+ so I would just add some $$ and go with a new set of 17 or 18 rims, How big of a tire can I go with stock hight ?