Max backspacing for 18" wheels in the front?

Thanks for the link. I actually read the entire thing before posting. Most of the info given is for 17's, and there was hinting at 18's might clear the tie rod end better.

I had found a post (can't find it now) that spelled out max backspacing for 15's, 16's, 17's, and 18's. The max backspacing got higher with each increase in wheel diameter. Anyone know this info?