The R8 has never seen rain. Also cup 2 in the rain is a bad day unless you drive miss daisyI'm not sure if you drive in the rain, but that's where you'll see the biggest difference between a new tire vs an old tire. The older tires have a lot less grip on wet pavement, but they certainly shouldn't explode.
I did it in 255/40/17 for s2000 square sizing. That size and 245/45/17 are the cheapest because they are the most popular. Ebay has them at $820-ish and that place has them at $1,048 (LOL). Tire rack has them at $850-ish and guaranteed not old tiresThe 305 rear's for my car are $170 cheaper than everyone else. And the 235 fronts were $200 more. So pick and choose what ones you buy I guess.
And expect old date codes. lol