If you're looking to buy an air compressor to run a tire machine, there are a few things you'll need to take into account. The most important factor is the size of the tank. A larger tank will be able to store more air and therefore run the machine for longer before needing to stop and refill. Another consideration is the CFM (cubic feet per minute) rating of the compressor. This measures how much air the compressor can output and is important for running certain tools such as impact wrenches. For most tire machines, a standard 6 gallon air compressor with a CFM rating of around 4-5 should be more than sufficient. If you plan on using other tools with your air compressor, then you may need something with a higher CFM rating. Always check the requirements of your chosen tire machine before making a purchase.