Alright i want to put rims on my civci, and im wondering how wide they can be. Any suggestions on Offset?
That theory doesn't really work out..The wider the wheel, the lower the offset you need to make it fit. As a rule of thumb, for every inch of wheel width above stock, you'll need 12mm less offset to get the same clearance behind the tire. Then you have to factor in the tire size... That's another ball game.
It's not a theory, it's just math. And it's just a rule of thumb because obviously a car can fit more than one size of wheel/tire without issues, but if you want the same amount of clearance, the rule comes into play. And really it just ensures clearance behind the tire, and does not take into account lowering the car which creates the tire/fender clearance issue, in which case a higher offset would be required to force the wheel more toward the inside of the wheel well.That theory doesn't really work out..
I have 4(technically 6 with 2 set of steelies) sets of wheels. Stock Del Sol wheels which are 14x5.5 +45, 15x6.5 +35 TE37 knock offs, 15x7 +42 Falken Hanabis and 15x7 +35 Enkie RPF-1's. I've had all 4 sets on my daily driver '99 Coupe. The only set that doesn't fit quite perfectly would be the 15x7 +35 Enkies. Sticks a little too far out and rubs the rear fender lip. Easy fix by rolling but meh. It'd probably be fine with a +38 offset.
So, the 15x6.5 +35 fit well, not 12mm less, only 10. The 15x7 +42 fit well, only 2mm less than the OEM Del Sol wheels.
Say I slapped 15x7.5 wheels, I'd need +21 offset wheels to make it work according to your theory. With that wide of a wheel, that low offset, the correct tire size, soft suspension and no significant modification to the fenders, you'd probably have issues.