When doing the ls400 brake conversion behind stock lS300 17's you need 15mm spacers and 50mm extended studs.

My question is, in order to keep the rear in line with the fronts and hopefully for a cleaner look do I need 15mm spacers for the rears too? Or a different size to get the wheels flush?

 

On mine I used 15mm spacers all around just so it doesn't look like crap with the front sticking out further than the rear. You can go a little larger spacer in the rear if you wanted.

 

Do you have a picture of your fitment with them on?

 

Send me a text and I'll send you a few pics. 979-758-1435 Jason