Yeah, modern tires are worth alot of time.
But it really should be run on vintage tires. The only problem with having the modern tires as an option is if you run the 917 online , i'll bet everyone will run the 'fastest' tire for fast times.
Really good car and hopefully we'll get a Ferrari 512 or a Lola T70 to run against in GTL.
I think i'll go for a few laps now that i'm all fired up