In theory a cut 24 inch bike tube as a flap should work. It doesn't work because the diameter is not large enough (it is not slack enough) to fit inside the tire on top of the tube. If it where a little larger diameter it might work. It does fit around the rim tightly and offers some protection but that doesn't protect the tube from tire irons when installing the tire and tube on the rim.
Don't ask me how I know :-(
New tubes are fragile. :-(
You are actually talking about rim liners. A flap goes inside the tire between the tube and the bead and will protect the tube from your tire irons.You put the tube into the tire, air up little, then insert the flap into the tire before you try to put it on the rim. On clinchers, the flap will also protect the tube from being pinched by the bead.
How to install a flap:
How to install a rim strip:
So new tubes are all synthetic and they don't take patches very well? What patch kit can I try that's available? Camel vulcanized not available and might not work on synthetic?
I have seen posts to the effect that patches don't stick well to these modern tubes, but if it was me, I would sure try patching it using a patch kit from "Slime" or one of the current manufacturers. Clean the tube well, follow the directions in the patch kit, and give the finished patch plenty of time to cure before you try the tube again.
Maybe I'm just lucky, but haven't used a flap yet and have done several new tire replacements with new tubes and no problems. I do run a layer of Gorilla tape around the inside of the rim though.
Nothing goes on top of the tube between the tube and the tire. I do run flaps, but many say they are not necessary and Ford never used them.
How do you avoid putting a hole in the tube when it is going on? I was putting relatively little pressure on a new tube with the tire iron and it developed a leak.
Ignatio, as pointed out, the 24 bike tube makes a rim liner. It goes on the rim, not in the tube. It is a smaller diameter than the rim so it is a firm, snap fit and won't move when mounting tyres.
A tube pinched by a tyre iron is a fitters fault, not a rim liner fault. I use tyre irons which have a pronounced curve on one end. This curve closely follows the profile of the rim, rolling around it rather than intruding into the tyre well. There should never be ANY contact between the tyre iron and the tube.
Hope this helps.
Allan from down under.
Put just a little air in the tube so it holds its shape, then you shouldn't have to risk pinch it with your tire irons.
Remember hot tires stretch better - without sun you may use a 500W halogen shop light as a heat source placed near, but not touching the tire for a while to warm it up.
Maybe a 27 inch bike tube would work. In principle it should. The 24's were just too small.
Flaps are thick, tough rubber, bicycle tubes are thin, somewhat fragile rubber. Fine for rim liners, not for flaps
Stop messing around with bike tubes and buy the flaps! Use plenty of baby powder on the inside of the tire, tube and flap when installing. I used big long screwdrivers as I did not have the tire irons and I did not put a hole in the tube!
Amazingly, motorcycle shops sell nice tire irons, for about $15. Good quality, correct shape even.