I got my toddlers bike second hand & it looked like tyres were a bit flat. We brought new tubes & when I went to replace them I found that the current ones inflated. It seems that I can pump & pump & still no more pressure is added past certain point. I.e., one can still depress a section of a tyre so the sides meet. When daughter is on the bike it looks like there is no air. With a single finger & minimal pressure I can flatten the tyre to the rim.
Is this normal or what am I doing wrong?