"90,000/60 = 1500 meters in 60 minutes"

You mean, 1500 m/min -----that is the tangential speed at the circumference of the wheel.

You know that

v = w*r

where

v = tangential speed

w = angular speed

r = radius

So,

1500 = w(0.625)

w = 1500 /0.625 = 2400 radians/min ----------answer.