I am in the market for a set of OEM C5 Z06 wheels and when I get them I plan on getting new tires. I will use the tires for autocross and daily driving. I would like to go a step up in size in the front and rear. I can find 275/40/17 tires easily, but 305/35/18 are very hard to come by. I also would run a 315/35/18 if I couldn't fint the 305's. I would prefer the front and rears to match. I've tried searching on various tire sites with no luck. As it looks now I will have to stick to the stock sizes. Any advice would be appreciated.