Just my humble opinion.
I use Nitto 555R's. 315 35R 17 rears, and 255 40R 17's on the front. I check the mfg date and change them every four years from mfg date. This is done on all my vehicles. The cobra, is way too costly a vehicle to cheap out on tires. My tires are two years old and if they last 4 years, I will be lucky. There is less than 8000 miles on the odometer. Car is stored inside, and during the winter months, the Cobra is stored on stands to releave the stress on the bearings. Bearings are re-checked for tightness at the end of each driving season.
But each to their own. Depends primarily on how you drive. Fun wow!!