... green ,gray(3) Bearing: Ball, roller, nylon or without bearing(4) Type: Solid, pneumatic, PU foam, semi-pneumatic, hollow etc.(5 ... ) Material of tire: Our rubber wheel has high natural rubber rate, high elasticity, rub resistance, natural rubber tire and steel ... size : 200x50, 2.50-4, 2.50-8, 3.00-4, 3.50-4, 4.10/3.50-4, 3.00-8, 3.25 ... , 3.50-7, 3.50-8, 4.00-4, 4.00-6, 4.00-8, 4.80/4.00-8, 5.00-6, 6.50 ...