I have them on my 400 and I have the bigger tires, 18/8.50-8. I started out without tubes but have since switched because both sides developed slow leaks. I can only surmise the leak was at the bead because since I have had the tubes installed, I have not had to add air.
I think my issues were related to the fact that the rims are not the best. I got my tubes from Tractor Supply so compare prices. I really think it depends on how good of shape your rims are. :fing32: