Tires
The only thing touching the road. Size is printed on the sidewall.
Signs it's worn: Tread under 4/32", cracks, bulges, vibration.
What's wrong with my car? · Tires
Bald tread, a sidewall bulge, or a slow leak?
Usually: Tires.
Bald tread, a bulge in the sidewall or a slow leak you keep topping up means it's time for new tires, in pairs at least.
The parts that fix it
See what these parts really cost for your car. Enter your VIN and we'll bring back 2-3 options from real sellers (dealer, name brand and budget), shipped to your door. Finding prices is free.
This is a first read from the symptom, not a diagnosis of your car. If you're not sure, have a mechanic confirm before you buy, and bring the prices you found here with you.