I don't even know if you can buy a good thick Goodyear or Firestone rear tractor tire tube anymore. You probably can, but it seems like everyone has the imports possibly with the name Rubber Master printed on them. I put a new tube (Rubber Master) in a 15.5 - 38 tire two weeks ago and have taken it back apart twice to find small breaks in a seam twice. The second time I had just put a patch on a break in the tube. Later that after noon I was working near by the tractor when out of the blue the tire just started hissing and was flat in minutes. It was another break not related to the patch I had just put on. Both breaks were on the back side where a tire iron never would have been. The rim is smooth as well as the tire bead. I have done many rear tractor tires with no problems. Just checking to see if this is a problem anyone else has had. Thanks.