Need Help Calculating Wheel Radius for Kinetic Energy

[tung]

Hi, I'm having difficulty figuring out the radius for this problem, I need the radius in order to figure out the kinetic energy:

A wheel has a thin 2.8 kg rim and four spokes each of mass 1.4 kg. Find the kinetic energy of the wheel when it rolls at 6 m/s on a horizontal surface.

I know that the I = 4(1/3 MR^2) + MR^2 and K = 1/2Mv^2 + 1/2Iw^2.

Anybody know how to figure out the radius, THANK YOU?

 

[WalterContrata]

Please try working out the answer, leaving R as a variable. What do you get?

Hope this helps...