Looking for wheels

Done quite a bit of measuring and re-measuring today and I'm pretty positive with the 8.25 rear and what I came up with I can fit a 15x10 with 4-3/4"- 5" backspace under there with no mods at all. But how much room do you guys recommend is safe for each side of the wheel. Thanks

You need at least a 1/2" of clearance to the quarters, the spring side can be a little tighter than that, 3/8" or so with 15" rims because of the taller sidewalls. I have a little less than 3/8" on my car but I also have 18's so there isn't much sidewall flex to deal with. I've never had issues with the tires rubbing on the springs, but I did get some minor rubbing on the inside wall of the wheel tub when cross-axling the car over speed bumps before I added my rear sway bar. No issues now that the body roll is less, but I run a 7/8" rear sway bar to accomplish that. With 18" rims you end up running out room in the wheel tub before the spring clearance becomes an issue though. That's why I say there's no point of doing a 3" spring relocation without a mini-tub, even the 1/2" spring offset I run gets you all the spring clearance you need and the wheel tub is the limiting factor then.