might buy some rims but i have a question

That will depend on the tyre and the rim offset, the big problem is the rear shocks.
Only sure way to see is to fit one, you may be able to just fit spacers on the rears.

 

I had 17x7 Rims with 35mm offset on my 87 GTS and they didn't fit the front wheel wells properly, would rub if i hit any kind of bump at more the 20-30km/h.

if you go with the 17x7 you may have to roll your front fenders, or you can just buy a ST165 which can fit the 17x7 rims ^^

 

offset 35 and 17x7 is no problem.

 

I believe you are driving an All-trac which has a larger/wider front wheel well then the 86/87 GTS

 

I drive a 86 GT with only the alltrac kit on it . I fitted the 7,5J but they did not fit on 0,5cm so 7 should surely fit !

 

true, if you don't exceed 215 width it will be ok. I could not fit 225 on the front, those rub in corners.

 

are your rims +35 lonewolf?