Alright so I am running the TRD lowering springs, wheels are 18" x 7.5 +42 and running 235/40 R18 tires I wanted the rear wheels to almost be flush with the fender to almost match with the front? Because they look so strange being so far inside the fender well. I am just not sure what kind of spacers to use, and what else may actually be needed.
Car currently

 

10mm will bring the rear in line with the front.

 

Would I require longer wheel studs? I have read about it briefly.

 

Yes, but most come with them. If you're fairly handy, they're easy to install.

 

Always get the spacers where the center bore fits...