so i bought a new pair of tubes for a bike i bought, suited for 19c to 23c,
and the front wheel went on perfectly,
different situation on the back wheel,
when i mounted the tyre it wouldnt hook the rim,
after closer inspection i realized that the solid rubber part of the tube that holds the valve in place was too wide to fit the walls of the tyre on either side,
this lead to pumping up the tyre and the tube popping out underneath the tyre.
you can see how the tyre wont hook the rim here…
and you can see here that the rubber holding the valve is too thick to fit the tyre in.
Tube is lying flat, so the tyre is pressing down on it. Try putting a little air in the tube to get it up inside the tyre, then try to get the tyre hooked on the rim.
Alternatively, try letting a little air OUT of the tube, push the valve stem (and with it the thicker bit of rubber) UP into the belly of the tyre and try to seat the bead while it’s up there.
if that fails you might need to try a different (lighter?) tube
Your issue isn’t the tube (or tyre) but technique. Deflate the tube completely, push the tube further inside the tyre using the valve stem and reinflate … checking that the tyre seats itself properly isinde the rim.
