I use the car bibles routinely, love the site and the guy who runs it is knowledgable, def the way to go. I had same issue with sizes, but just plug in sizes for tire you want and your good. (may have to scroll down a bit, its under the tire/wheel dimension tab)
Dont go beyond say +/- 1% on diameter/circumference or you;ll have awd issues and also speedo/odo will be off a bit which is obviously no good haha. Cant wait to see setup though, post up when you can!