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I'm going to jump out there and go for n00b...

I'm running a 1985 GSL 12a front disk rear drum and i would please like to know...

how thick of a spacer will i need to run to go from my stock 4*110 pattern, to a 4*100 pattern with either

(A) - Stock lugs

(B) - get aftermarket lugs.

then Question # 2

How much of an offset is still fully functional and necessary with said spacer when going to a 17" wheel and 205/40R17 tire ?

I'm finally starting my customization process and am starting... ground up

thanks you gents in advance.