4.00 - 6-Inch - 4 Ply Rubber Replacement Tube This 4.00 - 6"- 4 Ply Rubber Replacement Tube is just one of the components Marathon has to fit your needs! It is a Replacement tube for 13" Outside Diameter Tires. It is made of a heavy duty 4- ply rubber. This item gives you the convenience of fixing flats without having to buy a new tire. Maximum inflation is 30 PSI.Inflate with manual pump only. Features: . Replacement tube . 4 ply rubber . Fixes flats with buying new tire . Maximum inflation is 30 PSI . Inflate with manual pump only Item Specifications: Tire Type: 4.00-6 Tube Only Outside Diameter: 13" Width: 3.2"