What I need help with is this problem:

A point on the tread of a 16 inch (diameter = 0.406 m) tire is moving at 45,000 m/s. What is the angular rotation speed of the tire?

I know the answer is 2.2 * 10^5 rad/s but I do not understand how to get that. Thank you!

I know w=v/t so it is as simple as w= 45,000/(4.06/2)= 2.21674?
The diameter instead of radius threw me off I think