How to Tell if You Need New Tires: Spot the Signs Early

Ever seen someone blowing past you on the highway with tires smoother than a bowling ball? That’s asking for trouble. But here’s the thing—most of us are riding around longer than we should on risky tires, often because we’re not sure what to look out for.

First off, just checking if you’ve got enough rubber left isn’t as tough as it sounds. You don’t need a fancy gauge—just grab a quarter from your cup holder. There’s a simple trick with it that can help you spot a tire that’s getting dangerously thin on tread. By the time your tires hit this level, rain becomes your enemy, and stopping in time gets dicey.

But wear isn’t the only thing to watch. Sidewall cracks, odd lumps, and bubbles can pop up even if you’re not driving as many miles. Ever nick a curb pulling out of a tight driveway? That could cause damage you won’t see unless you crouch down and actually check. And no, those strange patterns aren’t ‘unique character’—they could mean the tire is close to giving out.

• Tread Depth: The Quarter Test and Beyond
• Sidewall Cracks, Bulges, and Other Red Flags
• The Truth About Tire Age
• When in Doubt: Simple Tips to Stay Safe

Tread Depth: The Quarter Test and Beyond

Checking tread depth is probably the most straightforward way to tell if your new tires are overdue. Grip goes down as tread wears, especially on wet roads where stopping distance can get scary fast. According to the National Highway Traffic Safety Administration (NHTSA), nearly 1 in 10 crashes on wet pavement relate to worn tires—so this isn’t just a hassle, it’s a real risk.

Forget any fancy gadgets for now. All you need is a quarter. Here’s how you do it:

1. Take a regular U.S. quarter and slip it into the tire tread with Washington’s head upside down and facing you.
2. If the top of his head is covered by tread, you’re good—your tires have about 4/32" (just over 3mm) of tread left. That’s the line where experts say you still have decent wet traction.
3. If you can see the top of Washington's head, it’s time to start shopping for replacements. You’re below 4/32", and your risk jumps up, especially in messy weather.

A lot of folks use the penny test where you check if you can see all of Lincoln’s head. The problem is, that test is too generous these days. Research shows grip takes a nosedive once you’re below 4/32"—not just the legal minimum of 2/32". Tires at 2/32" are plain unsafe if you hit rain or have to brake hard.

Here’s a quick breakdown of tread depths and what each one means for your safety:

Also take a look at the built-in tread wear bars (those little raised sections running sideways across your tread gaps). If they’re flush with the rest of the tread, your tires are toast.

If you end up doing the quarter test or spot low tread on just one tire out of four, don’t ignore it. Uneven wear can point to bigger problems—like bad alignment or suspension issues—that need fixing, not just swapping rubber.

Sidewall Cracks, Bulges, and Other Red Flags

When it comes to your new tires decision, the sidewalls say a lot. They're the part of the tire you can see easily, so don’t ignore them. Even if you've got lots of tread left, hidden issues on the sides can ruin your day—or worse, cause a blowout at speed.

Let’s talk about cracks first. Small cracks in the rubber, called crazing, show up over time thanks to sunlight, heat, and road salt. They may look harmless, but deep or spreading cracks can mean the rubber is dry or breaking apart. If you can fit your fingernail in a crack, that’s not normal—get your tires checked right away.

Bulges and bubbles are even scarier. These usually happen when impact (like slamming a pothole or smacking a curb) weakens the tire’s internal structure. If you see a bump or bulge, your tire is at risk for a blowout. No patch will fix this—it’s time for a replacement.

Any weird patterns like chunks missing, exposed cords or wire, or consistent flat spots should set off alarm bells. Don’t wait until you’re stranded. Here are the common sidewall warning signs to check for every month:

• Deep or wide cracks
• Bulges, bubbles, or blisters
• Chunks missing from the sidewall
• Visible fabric, cords, or wires
• Consistent flat spots (feels thumpy when you drive slow)

Veteran mechanics don’t mince words when it comes to these issues. As John Rastetter from Tire Rack put it:

“A bulge on a tire’s sidewall is always a sign of structural damage. There’s nothing temporary about it—replace the tire immediately.”

Let’s look at how sidewall problems stack up in the real world. Take a peek at this quick reference:

Ignoring these signs is playing with fire. Even if you’re not a car expert, doing a simple check for these red flags takes less than a minute, and it can save you from a dangerous—and expensive—blowout.

The Truth About Tire Age

Here’s a fact that surprises a lot of drivers: even if your tread looks fine, old tires can still be dangerous. Rubber breaks down over time, no matter how much or how little you drive. Sun, heat, and even just sitting in the garage can make your tire sidewalls dry out and crack. This process is called dry rot, and it weakens the tire from the inside out.

You might wonder, “How old is too old?” Most car and tire makers now recommend swapping out tires every six years, even if they don’t get much use. After ten years, it’s a hard no—no exceptions. Tires that hit this limit are pretty much a ticking time bomb, especially at highway speeds.

If you want to check your tire’s age, it’s actually pretty easy. Look for a string of letters and numbers along the tire’s sidewall. Find "DOT"—after that, the last four digits are important. For example, if it reads "DOT X000 XYZ 3520," that tire was made in the 35th week of 2020. This handy trick doesn’t take a mechanic, just a flashlight and maybe a little patience.

Here’s a quick breakdown of how tire age recommendations stack up:

Buy tires from a reputable shop, not an unknown seller online. Some shady dealers might offer seemingly new tires that have been sitting in a warehouse for years. That new-tire smell doesn’t matter if the rubber itself is past its prime. When checking your new tires, this date code is just as important as the tread itself.

When in Doubt: Simple Tips to Stay Safe

If you’re ever unsure about your tires, don’t wing it. Making a quick check is miles better than finding out you waited too long the hard way. New tires might seem expensive, but running old or risky ones can lead to far worse headaches—including blowouts or fender benders.

Here are a few reliable steps you can use whenever you wonder about the state of your tires:

• Check Your Tread: Use the quarter or penny test if you don’t have a tread gauge. Place a quarter headfirst in several different spots of the tread. If you can always see the top of Washington's head, your tread has probably worn down below 4/32 inch. It’s time to think about replacements.
• Peek at the Sidewalls: Look for cracks, dry spots, or little bulges. If you spot anything odd, like a bubble, call a pro or swing by your local tire shop before a drive out of town.
• Feel for Vibration: If you get weird shakes or thumps, especially at certain speeds, don’t just blast the playlist louder. Uneven wear or tire damage can show itself through new vibrations or handling changes.
• Know Your Mileage: Most tires are rated to last 40,000 to 70,000 miles, but life happens—potholes, curb scrapes, and rough roads can speed up the wear. If you’re closing in on those numbers or your tires are six years old, have them inspected by a shop.

Don’t just stick to visual checks. Tire pressure matters too. Under-inflated or over-inflated tires wear out faster and mess with your fuel efficiency. Grab a pressure gauge (most are under $10) and check your pressure monthly, including the spare.

If anything feels off, play it safe. Most tire shops will check your tires for free. And if you spot damage but ignore it, you could end up spending a lot more fixing your car than you would just getting new tires when you need them.

The bottom line? Stay curious about how your tires are doing. Trust your gut—and what you see and feel. Safe tires mean safer roads for you, the folks you care about, and even Clyde, who’s always riding shotgun in my car. When in doubt, don’t gamble—get those tires checked.