How can I change a scooter tire stem?

The schrader valve core on your scooter tire may be leaking and can be easily replaced. The tool and replacement core can be found in many tire repair kits costing as little as $10. Use the tool to unscrew the core. Then, screw in the replacement core and fill the tire with air. I purchased a kit at haborfreight.com, but places like Pep Boys also have them.

If the core is not the problem, then the tire must be dismounted from the rim. This can be done with hand tools, but it is not easy.

It depends on whether it's a tube or tubeless tire. If it has a tube, you just change the tube. You'll need to remove the wheel & pop one side of the tire off using tire spoons.

If it's tubeless, you may be able to replace it with the wheel still on the bike, but it'll be harder. In this case, you'll just be replacing the stem.

take it to tire guy/gal not really much else you can do