offset help

ok guys. its time for some new shoes. i have my 1st gen gs300 on air. i decided to put 20" wheels cuz of my kit. 20x8.5 and 20x10. i just need to know what offset to order. you guys think 15 all around will fit vip style of course. thanks in advance.

depends on what tire size and camber angle youre gonna run. Are your fenders modded?

^^ What he said ^^

Also, are you having custom wheels built, or are you 
choosing from a wheel (or wheels) that have pre-set
offset options.

For example, a cast wheel might be available in
20x8.5 +38 and 20x8.5 +25 (but nothing else)

If you want a VIP look and you're ordering custom
wheels, you might as well go a bit wider - something
like 20x9 +25 and 20x10.5 +25 is a decent place to start
for a mild VIP look.

fenders are stock but the rear lip is shaved. the wheels are made but they can custom the offset. u think +15 will sit flush

what tire sizes do u plan to run. how much your stretch and what tires ustretch
impact how much offset your car can take, but keep in mind that you're on air,
so it really wouldn't be that hard to get offsets you can roll on...

figuring out offset and stuff is one of the most fun things to do when ordering
rims. i think u should just measure how far out u wanna go from what you have.