Wheel offset

I was wondering if anyone had the info on the exact wheel offset for an '89 oldsmodile Cutlass wheel and for a '97 Malibu wheel. I'm trying to determine if the two cars use the same offset or what. I can't find the exact offset dimension anywhere and the wheel doesn't seem to be marked with the offset. It's usually stamped "ET" follwed by the mm of offset, but the factory wheels don't seem to have an offset stamp.

I actually put the Olds wheels on the Malibu and I can't really tell if they might stick out more than originals or not. I've heard that all the GM FWD wheels had the same high offset of maybe 40mm, but I'm not sure about these two applications. The car seems to exhibit signs of the original negative scrub radius being positive due to a higher offset of the Olds wheels.

You can determine this yourself, check this link, http://www.tirerack.com/wheels/tech/techpage.jsp?techid=101

How am I going to place a line from the exact inside wheel center to measure from to the wheel mount? Also, I don't have the Malibu wheels anymore to measure. It'd be easiest if someone had a source to the offset measurement for these wheels.