Michelin Sport 4S summer tire question

[FLYARMY]

I was just checking out tire specs to get new rubber for my Kia Telluride. Then I looked up what came from the factory on my 5 BW. Michelin Sport 4S summer that are speed rated for "Y", which is a maximum speed of 186 mph. Cadillac claims a top speed of 205 mph. Why wouldnt they have a better speed rated tire on these cars , while advertising a top speed of 205mph. Sounds like a liability issue if something went wrong tire wise.

 

[Merlette]

When the “Y” is in parenthesis, (Y), then it’s rated in excess of 186 MPH (“186+”).

 

[FLYARMY]

Why don't they just make a "Z" rating ?

 

[Merlette]

(Y) is the new Z

 

[ngoni]

Doing the math, it would likely take about 55 seconds or 9 miles for the 5BW to hit estimated top speed ~205mph. 4BW would top out in 80 seconds but only need 6-7 miles to get to ~189mph. If you can 'cheat' with a rolling start, a much shorter 3-4 mile distance could be used. Johnny Bohmer Proving Grounds in Florida looks like the best domestic option. Who's up for a road trip? Bring an extra set of tires.