hotwheels wide bodykit

I really like the look of the hotwheels wide body kit. The kit provides wide fender flares that i think look really cool, but what would i need to do as far as wheel and tire size, springs, and other mods to fill up the new larger gaps the new fenders will create. You can see the kit at http://www.mrbodykit.com/bodykits/00mustang.htmn Thanks for any help,
Kyle