I just bought some ZR1's with 275/40/17's.
The offset of these particular wheels are +38.

It seems that most people have the 56 offset and combine that with a 2.25" spacer in the front.
The 38 offset wheels have the wheel mount pad .7" closer to the rotor which I believe would require a 1.55" spacer to have the same offset. Is my math right?

Will 1.5" spacers be the ideal size for the front and back or should I purchase a staggered spacer setup? I am looking to keep the tires tucked tight under the fenders.

The car is a 84 z28 with the standard 3rd gen rear in it.

Thanks for any feedback
John

 

Just thought I would post a follow up about the 1 1/2" (38mm) spacers in case someone uses the search function.

I am using Aftermarket C4 zr1's with 38 offset making the combo zero offset when combined with the 38mm spacers.

Using the search function here I found many times people referred to Skulte site http://www.skulte.com/adapterfaq.html which recommends 2" spacers with 38mm offset, 17x9.5 wheels. On my car 2" spacers would be at least a 1/2" wider than necessary on the front. There is still 1/4" room to hard parts to allow deformation of the wheel under load. On the rear I would not like them sticking out any further than they are now. There is tons of room on the inside in the back.

I used 275/40/17 tires on the 17x9.5 wheels.