I'm buying some skinnies for up front and some wide wheels for back. My fenders and quarter panels are a little wider than stock so I'll need to do some measuring before ordering my welds.

Does anyone know how to measure backspacing so that I can get a wheel that fits?

 

https://www.rx7club.com/suspension-wheels-tires-brakes-20/rim-rubber-sizing-website-resources-160617/

 

Thanks.... I should have searched but didn't have the time.

 

I have a (blurry) picture of how I measured it on this page:
http://maxcooper.com/rx7/parts_info/ccw18/index.html

If you use a round pole like I did, keep in mind that there will be a bunch of parallax. I used another straight edge to line up the bottom of the pole with the scale on the ruler. Better to use a square pole if you have one around.

-Max

 

You could measure the backspacing on a wheel you have, measure it's distance from hitting stuff, and then combine those to determine your max backspacing. Be sure to account for suspension motion (the clearances are likely to change at full droop, normal height, and full jounce). Note that different wheel sizes will have different clearances -- for instance, you can run 7.5" backspacing with 18" CCWs, but I understand the 7.375" is the limit for their 17" wheels before you start to get contact with the stock trailing link.

-Max