Before you do that you need a valve stem puller if you do not have a valve stem tool.
Take the wheels off and take them to a tire shop as chances are the stem bases are in the tires and you really need metal stemmed tubes with 90 degree metal stems for it. Ask them to use the graphite tire lube when putting it back together. The metal stemmed tire tubes are a blessing just like the metal tubeless valve stems are.
I would use the shorty ones or the 90 degree (actually more like 45 degree), but be careful pulling the bent ones through, a little tricky.
Using a tire lube helps pulling them through.
Also using a small tire changer like the one Harbor Freight sells makes life a lot easier, as well as the proper tire lube. Putting a strap around the small tires also helps to seal the bead quickly, then put the valve stem back in.