Spare Tire: What It Is, Why You Need It, and What to Know Before You Use It

When your tire goes flat, the spare tire, a backup wheel stored in your vehicle for emergencies. Also known as a temporary spare, it’s not meant for long drives or high speeds—but it’s the only thing keeping you from being stuck on the side of the road. Most cars still come with one, even as run-flat tires and tire repair kits become more common. But not all spare tires are the same, and using the wrong one the wrong way can make a bad situation worse.

There are two main types: the full-size spare, an exact match to your regular tires, often found on trucks and SUVs, and the donut tire, a smaller, lightweight temporary tire that saves space and weight. Donuts are common in compact cars because they fit neatly under the trunk floor, but they’re not built for speed or distance. Most manufacturers warn you to drive no more than 50 miles and under 50 mph on one. That’s not a suggestion—it’s a safety limit. Driving faster or farther can damage your transmission, throw off your handling, or even cause the donut to fail.

Many people never check their spare until it’s too late. A spare tire that’s flat, cracked, or underinflated is useless. You wouldn’t drive without checking your oil, so why skip checking your backup? The average spare tire loses pressure over time—even if it’s never been used. And if it’s older than six years, the rubber can dry out and crack, making it unsafe. Look under your trunk or behind the rear seat. Is the tire still there? Is the valve cap on? Is the jack and lug wrench still in the kit? If you’re not sure, now’s the time to find out.

Some newer cars don’t even include a spare anymore. Instead, they come with a tire inflator kit or sealant. These work for small punctures but won’t fix a sidewall blowout or a shredded tire. If you drive on rough roads, off-road trails, or in remote areas, a spare is still the smarter choice. Run-flat tires let you keep driving after a puncture, but they’re expensive to replace and can’t be repaired. If you’re replacing a tire, you’re replacing the whole wheel.

Knowing how to change a tire matters more than ever. Traffic is heavier, roads are rougher, and breakdown services take longer. If you’ve never changed a tire before, practice in your driveway. Watch a quick video. Get familiar with your jack, your lug wrench, and where the spare is stored. Don’t wait for a flat in the rain at midnight to learn how.

And here’s something most people don’t think about: your spare tire affects your car’s balance. If you’re driving on a donut, avoid sudden turns, hard braking, or high-speed corners. Your car’s stability control system isn’t designed for mismatched tires. Even a full-size spare that’s newer or older than your other tires can throw off your ABS and traction control. It’s not dangerous if you drive carefully—but it’s not normal either.

What you’ll find below are real stories and practical guides from drivers who’ve been there. From how to tell if your spare is still good, to why some mechanics refuse to install donuts, to what happens when you drive 100 miles on a temporary tire—these posts give you the details you won’t find in your owner’s manual. No fluff. No theory. Just what works when you’re stuck and need to get home.