Why is the Brickyard 400 not a restrictor plate race since it is a 21/2 mile track?

Question

Why is the Brickyard 400 not a restrictor plate race since it is a 21/2 mile track?

Answer 1

The curves are so flat that the cars can't build up enough speed to require the restrictor plates.

Answer 2

Can you give more information as I do not understand the question. I assume by the Brickyard your talking about Indy, but which race and what bikes I have absolutely no Idea. I'm asking because I like to know about Motorcycle Racing and I don't quite understand what you mean by a Restrictor plate. Please elaborate.