[Purist]

I think the very fact that they're going to Indy shows that they want a showcase event in the US, and running the Oval T1 banking will only enhance that aspect.

Pirelli has experience with rovals from their time in Grand-Am, as well as Rockingham with British GT. And assuming they've done anything with GT3s at the Nurburgring, they have experience dealing with extreme and unusual loads. For F1, they have to design for a number of high-load circuits, like Spa and Suzuka, plus they have Zandvoort coming, which means Scheivlak and a new, banked Luyendyk Bocht. IGTC also has Spa and Suzuka, as well as Bathurst with its lateral loads and compressions.

More directly though, they had to bring a tire capable of handling at least some banking to Las Vegas anyway. Ovals with moderate to higher banking have the outside of the apron, before you get to the oval turn proper, banked to a lesser extent. So inside the 18-20-degree main banking at Las Vegas, that outer portion of the apron may be 6 degrees or so. (The tri-oval is banked 12 degrees, btw.)

Sebring's claim to fame isn't its long straights, but regardless, the figure I'm recalling for the Ullman Straight is 0.595 of a mile, which translates to 957 meters, so no it isn't as short as you suggested. I've seen figures of 872 and 975 meters for the front straight of the Indy roval, which is a bit confusing, because that length for both the first iteration of the MotoGP layout and the IndyCar configuration should be the same. Furthermore, while the front straight at Suzuka may be of similar length to Indy, the run from Spoon to 130R is 1,200 meters, not 950. In fact, almost every recent or current F1 circuit has a straight or stretch of a kilometer or more, with some going notably beyond that (Fuji: 1,475 meters); you can add several of the US road courses to that club as well: Road America, Road Atlanta, and VIR to name just a few.

And unfortunately for your assertion based on IndyCar, the SCCA Runoffs layout would throw those low-downforce setups out the window, because with the extra infield loop, you now only have one long straight/stretch, not two. Even if Turn 15 of that layout (T14 for IndyCar) is flat-out all the way, a 3,700-ft run is only 27% of the lap, with no other particularly long straights. Using the current equivalent of the F1 layout, you get a 6,300-ft run, translating to 47% of the lap. So what gives you those compromised setups with IndyCar isn't just the front stretch, but the 950-meter infield stretch (counting from T4 to T7) in addition to it.