OK, I have been on the phone with Nitto Tire directly, and unlike some other companies, they are very in tune with their customers, they are willing to create new tire sizes if the demand is brought to their attention. I have discussed with them the need for a 305-35-18 (and the ABS problems that the 315-30-18 sometimes creates), and that if they simply made a 305-35-18, that they would sell like hotcakes to the entire 997 platform Porsche community, and corner the market overnight, because in reality we don't have any other options since the RA1 went away, as far as a treaded R-comp is concerned, since everybody dislikes the R888.

If you want to run the 315-30-18 rear, then request a 255-35-18 front size.

They have created sizes in the past (for much lower volume cars), and a new one for 2011 simply from requests they get through their website in the "contact us" link. I have no doubt that if everyone who is interested in this type of tire (and not a hoosier) would go to their website and flood them with requests for a 305-35-18, then they could have it available to us for the 2012 track season. But now is the time to start flooding them with requests.

If you liked RA1's, and want a long-lasting DE tire in the 18" size, I promise you this is it. I've been using them on my E46 M3 for years, and they are fantastic. We need more 18" options, so even if you don't want to run them, please go to their site and request the 305-35-18 size. I've been filling it out multiple times a week, but we need different people to request to get this going. Please keep filling this out and help us get the tire we need!

Here is the link directly to their contact page.
http://www.nittotire.com/Contact