rear tube blowout, how come?

I have a 720 standard that has 18.4 x 30 rear tires. At some point in the past, someone cut the rims and welded in 4 inch spacers. The tractor still has 18.4's on it, they just set wider than would be normal. I had an old tire blowout the side so I found a good used tire and a new tube and put it together. That lasted for about 3 months and then slowly went flat. Broke it down and found two small holes on the rim side of the tube, probably from rust flakes. So I patched the tube and cleaned up the rim and reassembled. then 4 months later, out of the blue and the tractor is setting there flat again. Take the tire off and break it down, this time the tube has a blowout on the rim side about a foot and a half long. What would cause a blowout like that? this tube isnt even a year old. Is it possible that with my rim being wider that the 18.4 tube isnt able to handle stretching that much and I need to get a tube for a 23.1? Local tire guy says no, but I am still wondering. What would make a tube blowout on the inside facing the rim? After the first time the tube got the two little pin hole leaks, I cleaned it up and put a good coat of rust converter stuff on it to make it a pretty good finish, but is it possible it is still rough enough to pop the tube? Getting tired of breaking down this tire so appreciate any advice before I put another new tube in it this time.

Likely, the tube was pinched between the tire and rim upon assembly.

You wrote: "a blowout on the rim side about a foot and a half long."

(1) could possibly be a poor quality tube to begin with.

(2) You may have "scratched the surface" (rather deeply) in your previous dismount/mount of assembly and the tube eventually gave way at/along the injury. Try to hold squirming/twisting/etc/ of tube to a minimum and make D-DOUBLE-DARN sure there are no burrs or roughness on the inside of rim...especially where repairs were made to rim. KEEP IT SMOOTH!!

GOOD LUCK...Rear Flats NEVER happen at an opportune time or place. We've all been there at one time or the other OR will be at some time in the future!! lol!!

Rick

When you inflated the tire to seat the bead did you let the air out again to let the tube relax? If not, the tube was stretched along the rim.

I have the same problem with a 16.9/18.4 tube that I bought last year for my 18.4 x 28" tire. It was a cheaper (not cheap!) foreign made tube that looked small to begin with....and has not held air since about a month after it was installed. The dealer that only had really expensive tubes warned me about cheaper ones, but I figured I wasn't using fluid so I would be ok...guess not.

I have found that the new tubes of today are not of as good a quality as the older ones. I have had several that go on the seams. Just my own experlence.
Bob

Are you putting talc on the tube so it can squirm around in the tire like it wants to? If it was streched too much in one area, I can see it tearing over time.

If they make a heavy duty radial tube for that tire, spend the extra bucks and use that. Like the other post said, once the tire is out against the rim. let the air out of the tube and then reinflate it. Do not use a 23.1 it will be too big and wrinkle, usually causing a flat at the wrinkle.

even though my rim is now wide enough that it should in actually have a 23.1 tire on it? It came with these expanded rims and 18.4 tires and I haven't been able to afford new 23.1's so I am trying to make do. My local tire guy says the 18.4 tube should easily be able to stretch that much but for some reason it blew out.