I know this is pretty Mustang specific, but I figure I should go ahead and appeal to the Oppo hivemind in case anyone has any answers, since so far the Mustang forums aren't helping too much.
So my instructor at the HPDE at MSR Cresson (writeup here) said he is able to hook me up with some scrub Pirelli P-Zero LM slicks, coming from a former ALMS team for a kick ass price. The problem is these only come in size 305/660 18. So obviously that second number is not normal, but I found out that Pirelli labels all their slicks that way. What I am more concerned about is the 305 width tire. So that rim in the picture is the SVE Drift rim, and is a decently light and cheap rim that can be had in 18X10", which is what I would need for the 305's. They have a +43mm offset. Now I have been trying to figure out what kind of spacer or camber I might need to run in order for these to fit, but two nights of research have yielded nothing. I do know one guy that is running these with 285's all around with just -1.3 camber, and that Sam Strano runs an Enkei rim that is 10.5" wide with 315's and a 5mm spacer. Also this site has a cool thing where you can spec out a wheel, but I have no idea what 660 in Pirelli speak equates with normal tire measurements. I just wanted to see if anyone on here had any experience with running a wide tire with this, or any suggestions on figuring out the best way to see if these will fit. I am still waiting on a call back from Sam Strano, but until then, any suggestions are appreciated!