You should be good with a 60 gallon tank as long as there are enough hides for both of them and they are the same gender. Do not house axolotls of the opposite gender together.
My axolotl is spoiled with a 75 gallon tank. 55 is definitely big enough but keep in mind the tank should be longer than it is tall. They require a minimum of 29.5 gallons for one axolotl
Axolotls are actually so weird to keep. A lot easier than people make them out to be once the tank is cycled since thatÂ’s the hardest part. But they have such odd requirements and healing fixes