This tip comes from my lovely friend Cinda Roberts. It's about checking your tires to see if you need new ones.
Take a penny and place it with the head pointing down into the grooves of your tire.
If any of Lincoln's head is covered by the grooves of your tires then the grooves are still deep enough. You shouldn't need your tires replaced.
If you can see all of Lincoln's head and hair then the groove are no longer deep enough and you may need to new tires.
Check all four tires and the spare in a few spots each.