Hey BigRod, You don't need spacers to run bigger tires. I'm running 37x12's; I think there's a 1/4" spacer for the leaf springs but I don't have spacers. Been running for a year and a half like that. You just air the tire up half way then put it on there, tighten the bolts up snug, air it up, then tighten it with an impact, make sure it's touching all around and you'll be good. Make sure you let the air out before you take the tire off or on the last bolt, you'll strip the threads.
http://i565.photobucket.com/albums/ss100/waterfowlwarriors/P1010932.jpg