What size spacer do I need on the front, to use my 17" OEM staggered rms ?

5mm in the front will do it.

It will also depend on ride height and camber settings.
5mm sounds like a decent first guess, but it's always a crapshoot trying to guess what will/won't rub without trial and error.

I didn't have any rubbing with my Hoosier R-comps on stock contours. Then again, I have a square setup

245/40 on a 7.5 rim is pretty wide, and you might get a sloppy sidewall and poor contact patch compared to a 235/40 or 225/45.

I have no problems running a 245/40 Kumho MX on stock 8.5 rims in front with no spacer.

245/40 on a 7.5 rim is pretty wide, and you might get a sloppy sidewall and poor contact patch compared to a 235/40 or 225/45.

I have no problems running a 245/40 Kumho MX on stock 8.5 rims in front with no spacer.

The only rubbing I get up front on 8.5" Contours is at full lock, usually when pulling into a parking space. I also have 245/40 MX's on 8.5" Contours all around.

It will also depend on ride height and camber settings.
5mm sounds like a decent first guess, but it's always a crapshoot trying to guess what will/won't rub without trial and error.
I should have put a disclaimer on my post. I have no issues with a 5mm spacer on the front wheels with my setup. I run staggered DS-II's with 245 tires all around in BS Solo II. My suspension is stock. I need a 5mm spacer to keep the tire out of the strut.

That is what I needed fellows !!, THANK YOU, very much, I will try the 5mm and put the 245's all on 8.5 wide rims...I have like 5 sets of staggers...gotta love eBay....Bob