Nope, not street legal.
I track the car and was tired of "agricultural racing" so I got more grip. Lots of warning at limit, then a slow gradual release. Easier to throttle steer with the good feedback.
On Roger Kraus tech sheet, x marks the serial number molded into each tire. It's only on one side of each tire.
http://www.rogerkrausracing.com/TechSheets/fit.shtml
Here's what the serial numbers look like. There's also the tire model number molded in, but that's 4 or 5 digits in a little oval. Find the serial numbers then you can match them to the appropriate rims.
You can see on the side of the tire "Racing Use Only Not for Highway Use"
They behave the same as billboards. A little flat-spotting, rough until warm, but when they're warmed up (3-4miles) they're smooth and sticky. They do throw rocks.
I think they look like a hundred bucks. Love 'em.