Sears Fat tire mini bike tire size?

I have a few Sears mini bikes with the swingarm/motor plate.

I am wanting to build a fat tire bike pretty much the same as the Sears fat tire mini. Does anyone know off hand the front and rear tire size and rim/wheel size these had stock?

Thanks ahead of time!
mine are 18x9.5x8 just like my golf cart

i have tractor tire tread on back, and i am going to replace it. to hard for the kids to ride.

i am looking for some brake parts if any one know where i can get some.