Incorrect settings alter a car’s handling, possibly causing it to pull to one side and causing actual damage to the tyre carcasses. It is critical to maintain the proper tyre pressure. It’s a good idea to get a small tyre pressure gauge, but there’s no point in using a foot pump instead of garage air lines. One disadvantage of checking at a garage is that the tyres may be hot, which raises the pressure; readings should be taken when the tyres are relatively cold, most likely at the start of the journey.

It is worthwhile to increase the pressure by two or three pounds all around for a long highway trip. To use it, remove the dust cap from the tyre and press the gauge firmly against the valve to ensure that no air escapes. Check the reading and add some air if necessary. Air lines vary, but typically, you simply connect the lines to the valve and press a button to inflate them. 

Always replace the dust caps and do not forget to check the spare tyres well.