Tires: just check to make sure you still have four on your car, and you’re good to go! Turns out there's a little more to tire safety than just visually confirming they're still attached to your hooptie. Every month you should check the pressure on the Four Horsemen of The Apocalypse (that’s how I refer to the tires on my 2009 Prius, but choose the Golden Girls, the Beatles, or whatever foursome you personally connect with).
Proper tire inflation and tread means you’ll be safer on the road, and get better mileage; being alive and saving money = two great reasons to do these simple checks.
Start with cold tires, ideally not after you’ve been Tokyo Drifting down hot asphalt.
Check the PSI (pounds per square inch) recommended for your car, listed on the sticker on the inside of the driver’s door.
Unscrew the valve stem cap. It’s the little pencil-sized piece sticking out 1” near the hubcap.
You’ll need to have an air pressure gauge to measure the amount of air the tire. You can either buy one to keep in your car, or find one at most gas stations. Take your gauge of choice and press it evenly into the valve stem. The air pressure will push a small bar out from your gauge, marked like a ruler to show the tire’s current PSI.
If the measurement is lower than the recommended PSI for your car, you’ll need to fill the tire with air. Check the pressure as you go until you’ve reached the correct PSI. If you’ve overinflated the tire, just press down on the center of the valve stem to release some of the air.
Replace the valve stem cap and repeat with the remaining three tires.
Don’t Tread on Lincoln’s Head:
While you’re down there checking the tire pressure, take a look at the tread on each tire. If the tire tread is heavily worn down, it’s time to thank him for his service and buy a replacement. The U.S. Department of Transportation (Czar of Cars would be a fun rebrand, not that they asked) recommends replacing tires when they reach a tread depth of 2/32”. Don’t have an elf ruler handy for this very specific measurement? Don’t worry, because you can measure this with a penny (pretty sure that’s all they’re good for anymore...well, tire tread measuring and fountain wishes #nichecurrencyvalue).
Take the aforementioned penny, put it into the rib of the tire (the raised portion of the tread), and turn the coin so Lincoln’s head points down. If you can see Honest Abe’s chin, nose, even eyes, you’ve got a safe tread depth. If you can see the top of his head, your tread is low and it’s time to replace it. In case you forget, I came up with a really jazzy little song to help you remember:
See Lincoln’s head? You got no tread!
See Lincoln’s face? No need to replace!
Air Pressure Gauge -