With the Forgestars you would still need to run spacers right?
It might not have the deepest concavity but the AME TM02 might be an option for you.
Considering you would need to run spacers anyways you might as well just get adapters and find some 5x114.3 wheels.
Our RB V1 FRS was sporting some
AME TM02's 5x114.3 18x10 -5 front with 225/40/18 and 18x11 -40 rear with 255/35/18
We started out with 10 +15 and 11 +10
I have seen so many V1 kits with one piece wheels and sadly they just aren't spaced out far enough and often look a bit sunk. It's unfortunate that these fenders are almost too wide for an affordable one piece setup. Spacers are likely to be inevitable.
AME just released some 18x9.5 and 10.5 +22 wheels in 5x100 so we're currently running a grip oriented setup of
18x9.5 +17 NET with the use of a 5mm spacer 255/35/18 front
18x10.5 -16 NET with the use of a 38mm spacer 285/30/18 rear
Camber is set to -2 deg front and rear
Car felt amazing with the grip setup. Sadly she's back under surgery for the V2 kit, getting ready for SEMA. the setup will be back on in a month for actual track testing.
Photos of both setups:
Stretched
Grip
