For regular "street type" tires I like the Goodyear F1 Eagle GS-D3 tires in stock C5 sizes. Check out Tire Rack ratings for this tire. I've never "lapped" with these although I have run at least three autocrosses on them. On a 30-second course I find them about 1-sec behind Hoosier tired C5s. With the original EMTs I was running a good 2-3 seconds behind. Great tires for everyday driving with low noise and smooth ride. Its not a run-flat so I made up a fix-it kit with plugs, aerosol sealer, air compressor, t-handle plugger, gloves, pliers, tarp. I won't use the sealer except for emergency purposes when I have to get out of "Dodge" quickly since the sealer will ruin the air pressure sensor. These tires are also great for driving in the rain. Unlike some Corvette drivers, my vette is driven in most weather conditions (except snow, ice - not in Northern CA anyway).
