Originally Posted by Geepig

If you are using cheaper foldable tires it helps if you unfold them and keep them somewhere warm for a while so that they have a chance to unkink a bit.

When fitting, they might be difficult to centre and may even pop off then or during your first ride. To avoid that, fit the tires and tubes with a little air in the tubes so that they just take a round shape. Centre the tire on both sides as best you can. Give a couple of pumps using your pump, then check the tire is still centred and centre it if it is not. A couple or more pumps and recheck - and so on until the tire is up to pressure. I then fit the wheel and give the bike a gentle ride around my garages, and recheck that the tire is still centred.

It takes a bit of time and effort, but that is the price one pays for cheap tires. Once they have been ridden for a bit, they take their original tire cross section and should cause no further problems.