Speed limits here where Im at are 55mph, 65mph and 70mph (highway speed limits) depending on the highway. But that doesnt mean you cant blow the carbon out every now and then. My old white Nissan Twin Turbo Z I hit 168mph it it and it was still pulling. This new red one I have hit 120mph, but until I get new back tires, I wont go any faster. When I bought the car it had two new Yokohama S-Drives on the front (speed rating of Y), but the backs are older (not "Y" rated) and have little tread left. Ordered two new Yokohama S-Drives for the back on Monday and they should be here tomorrow. And that means I get to "Smoke" the old ones !!!!