If you are running the front GTA rims all the way around then you probably get by without spacers depending on how much tire you want to run. If you are running front & rear GTA rims then you will need to run the front rims on the rear & the rear rims on the front with a spacer, probably about 3/8" or so. I run fronts all the way around with no spacer, so my front passenger side rubs slightly at full right tilt. This can sometimes be corrected by centering the body on the frame more, which sounds like more work that it is worth to me, but just my opinion. I think that Summit has some spacers, but not sure. HTH