I want to determine the dimensions (radius, number of teeth) of a pulley that suspends two masses equivalent
I have a system that consists of a pulley on which to hang two masses equivalent and I know the value of this mass and what I'm looking for is a method that I can use to determine the value of the radius or well diameter of this pulley and the belt on which is mounted the two masses
The sizes you use all depends on the purpose that these components are to be used for. The image you have attached looks to me like a diagram in a basic mechanics text as you would find in an explanation of how a belt drive works. There is no information provided in your question that would enable anyone to determine any details required to design a belt and pulley drive system. If you desire to design a belt / pulley system to work you need data, power to transmit, speed and the like, you just can't guess the specifications of the components required. To learn how to design a usable belt drive, reading a few basic mechanics text would be a good place to start as to design one, not an overly complicated process. As long as you know the theory of how belt drives work. there are many calculators available on the web that will even do the math for you.