Wheel offsets (backspace) for GT4 flared car

What are your rim widths?
My fronts 10x17 with 5" BS
rears 12x18 with 4.375 BS. I could have even gone to 4" on the rears.
Nice fit.
BTW, I have Wilwood hats that move the wheels outward by 1/2" over stock
Will

Sorry I did not clarify

Fronts are 10" wide

Rears are 13" wide

15" diameter rims

For my GP4 I used the same backspace as my GT5;

10x17 and 4.625" BS
13x18 and 4.75" BS

Two things worthy of note;
1. different wheel suppliers quote backspace differently, BS quoted above is to tire bead lip
2. More important than wheel dimensions is the flares, whether steel or fiberglass and supplier, as there are most certainly a number of variants offered. Fiberglass flare fitting is somewhat predetermined, but steel is very dependent on the fitting process as most need at least some metalwork. For a comparison I'd recommend dropping a plumb bob at the outer flare lip and measure the distance to the hub wheel mounting flange.

Julian

quote:

For a comparison I'd recommend dropping a plumb bob at the outer flare lip and measure the distance to the hub wheel mounting flange.

Drop the plumb bob when the suspension is at ride-height. It won't be correct if the suspension is hanging.
Will

I have a question to add. Should the wheel sit evenly with the outside of the flare or is it better to have it sit a little bit inside the flare and how much?
Thanks

I am running Hall GT4 glass flares (original) and my current wheels are at least 1.5 inched inside the inner lip of the flare.

Would prefer them sitting closer to the edge

I have my rears in about 3/4". The fronts are about 1".
I would keep the fronts in at 1" because of the turning but the rears can be flush with the lip as they arch inwards as they travel upwards.
I kept mine in a little because I may go to a wider (345) tire if they become available.
PanteraPat, why were your wheels positioned so far in? Did you buy the car that way or did you order the wheels?
Will

Had the wheels made to duplicate Campy GT4 rim back spacing