muffler bearings
Heffay- Talking about the accuracy of tire guages, whether to check hot or cold, etc. Pros do a spot check- if you have the right tire pressure, it goes up about 10% when warm. Of course to be really scientific, you need the proper seasonal air in your tire, which is why you need to change your tire air twice a year. Winter air is denser than summer air.
You already knew that, right?