30x9.5r15 vs stock tires
 

Please excuse me if this has been asked but search wasnt finding anything...

I am wondering if there is a big difference in 30x9.5r15 and the stock 235/75r15? The tire calculator says there is only an inch difference in diameter. Has anyone dropped down a size like this? My truck already sits too low for liking so I am wondering how much a difference there really is.

You are correct. The difference isn't much. I think the stock size is something like 28.9" or 29", so a 30" tire isn't that much of a difference.
I have 30" tires on my stock ride height. It sits higher then my buddies (Stitch17) Blazer when they're parked next to each other, but it's not that big of a difference. Just noticeable.
If you're looking to go higher then you'll need some sort of lift be it suspension or body.

I currently have 30" BFG a/t's and I decided I couldnt drop down a size. I went with 30/9.5x15 Bridgstone Dueler Revos. I couldnt pass up the buy 3 get one free from firestone. Should be installed on Monday, cant wait!