How to read tire markings: uncover the mystery of tire markings

Advance Auto PartsLooking to read the life story of your tires? Well, to a degree, you can. Each car tire reveals its uses and specs through a code that consists of numbers and letters, a code that is usually found in the tire sidewall. But, because the code is constantly changing to provide more information, it may look like a hodgepodge that’s as clear as an obscure foreign language.

Fortunately, with a little help, anyone can understand what’s written on their tires. And, once you do, it can make all the difference in what you purchase and how you use the tires.

To start, the majority of tires are given a measurement from the ISO metric sizing system.

Discover what an ISO metric tire marking can tell you:

Starting with the ISO code, you will often find a letter(s) on the tire that tells you if the tires are intended for a:

  • P: standard passenger car
  • LT: a light truck
  • ST: special trailer

If you see the letter “T,” it stands for “temporary” and is often written on spare tires and other emergency tire types.

You will also sometimes see a 3-digit number, which provides the tire’s nominal section width. This is usually measured and marked in millimeters, from the widest point of both outer edges.

The aspect ratio is also listed on the tire’s sidewall, and this is usually a two- or three-digit number that is written as a percentage. If this is not listed on your tire, then your tire’s aspect ratio is the standard 82%, which means that the sidewall height is 82% of its width. Any other measurement will be marked.

Finally, there will sometimes be a letter on the tire that tells you what the fabric of the tire is constructed of:

  • B is for bias belt, which is great for a rough ride.
  • D is for diagonal.
  • R is for radial. Radial is one of the most prolific tire materials on the market.
  • If there is no letter marking, then you likely have a cross ply tire.

The load index is a tire marking that denotes how much a tire can carry. For example:

  • A code of 60 means a tire can carry up to 550 pounds.
  • The highest code is 125, which can carry approximately 3,600 pounds per tire.

Finally, once you know the load index number of your tire, you can begin to pay attention to its speed rating. This tells you how fast you can go based upon your specified load index. So:

  • Code A1 means that you can go 3 mph at the specified load index.
  • This goes up to code Y, which allows you to travel up to 186 mph.

These are the basics of how to read tire markings. They are important to know when you’re shopping for replacement tires or just need to be educated on what your car can do.

Editor’s note: Shop Advance Auto Parts for a wide variety of tire gauges, tire repair tools, accessories and more. Buy online, pick up in store. 


Graphic courtesy of Consumer Reports.

How to Diagnose Engine Noise

Spartan engineEven those with lots of experience in car repairs can be fooled by the meaning of engine noises. To make matters more confusing, sometimes minor or innocent-sounding sounds may signal a severe problem, while a loud, menacing thud might be fixed with a $20 part.

But, here’s something that’s for certain: you shouldn’t ignore car engine noise. Doing so could lead to a catastrophic situation where your engine needs to be replaced. Plus, disregarding engine sounds could threaten your safety–and result in a breakdown at the worst possible moment.

While you always have the option of taking your vehicle to a mechanic for a diagnostics test, you can often get a good idea of what’s troubling your engine by listening to it.

General guidelines about engine noise

See if the car engine noises you’re hearing match any of the following sounds. Then look at some common reasons for that sound, and begin your investigation there.

  • Whirring: Could mean a bad water pump, power steering pump or alternator, or low power steering fluid level.
  • Knocking: Could be an issue with the distributor cap, timing chain or spark plugs.
  • Pinging: Could indicate a problem with the crankshaft, timing gears or transmission mount.
  • Hissing: Could mean a problem with the cooling system, exhaust, catalytic converter or vacuum line.
  • Popping: Could be an issue with the ignition wires, air filter, distributor cap, ignition module or engine compression.
  • Grinding/screeching: Hearing these engine sounds when you turn the ignition could mean a starter issue. But, if these sounds occur when you apply the brakes, it likely indicates worn brake pads or rotors.

Again, don’t turn your back on car engine noise, and hope that it’ll just go away on its own. Chances are it won’t, and you’ll wind up with an even bigger problem.

What did we miss? What strange noises have you diagnosed in your engine? Tell us in the comments.

How to Clean Car Headlights

You may not think about cleaning your headlights except for doing a quick wipe when you’re washing your car. That’s an important step; however, it’s necessary to take your headlight cleaning a little further, especially when they look foggy. Having dirty headlights filled with buildup can make your lights look dim, potentially placing you at risk for accidents. You may even get ticketed by a highway patrol officer if he or she feels your lights are dulled enough to pose a risk to you or others on the road.

Fortunately, cleaning your foggy car headlights can be as easy as brushing your teeth. Here’s how to do it.

Headlights of a Bloomington Mustang


Good for beginners – A new DIYer will be able to complete the project


Estimated time required

1-2 hours


What you’ll need

  • soft, dry cloth
  • rubbing alcohol
  • sandpaper: 400, 1200 and 1500 grit
  • spray bottle filled with water


The toothpaste method

It may seem strange to use toothpaste to clean your headlights, but it works. Just make sure you’re using regular white toothpaste. Mint paste or those that are designed for whitening or other special purposes can damage your headlights.

Step 1: Take the plain white toothpaste and squeeze it onto a soft, dry cloth. Wipe your headlight lens in circular motions in small sections until the dulling grime is removed. Don’t try to cover a large area. Instead take on small portions of the bulbs and concentrate on them until you get a clean shine.

Step 3: Rinse the area with water and wipe with a clean, wet cloth. You can then apply some polish specially designed for headlights if you wish.

The lasting clean method

You can also use sandpaper to clean headlights and do what is known as a “lasting clean” method. This will not only clean your headlights, but prevent them from becoming dirty again in the near future.

Step 1: Clean your lenses twice with rubbing alcohol and then wipe with either paper towels or a clean, dry cloth towel.

Step 2: Use a spritzer bottle of water to “wet sand” your headlights. Do this thoroughly with the 400-grit sandpaper. You will likely begin to see the factory coating come off of the lights. Keep on sanding until the coating is completely removed.

Step 3: Then, you will have to eliminate any scratches left behind by the 400-grit sandpaper by using the 1200- and 1500-grit paper. If your car headlight bulbs have an interior texture (you will know because you won’t be able to see the light bulb inside), then you can usually finish the job with the 1200-grit paper.

Step 4: Finally, wipe them off with more dry paper towels or a clean, dry cloth.

Complete headlight restoration may require a little more than a home remedy can offer. Try a headlight restoration kit if you’re stumped, and watch our videos to help you tackle the job.

Wash? Wax? Why bother.

Advance Auto PartsWouldn’t you know it? At long last, I not only washed but also detailed, to the best of my ability, the car this past sunny weekend.

Not even a couple of days pass before the inevitable happens. Rain. All last night. And this morning.

Serves me right. The Wash Your Car Now gods are getting back at me for waiting too long. (Pity, the billions of bugs that met their fate on my front bumper. Alas, the caked-on muck and sludge atop the once proud clear coat.) Apparently, I haven’t sacrificed enough personal time in order to surround myself with car wash products to appease the auto overlords.

What can I say? I HATE when it’s time to wash my car, and don’t get me started on waxing. There, I said it, even though I love and value cars and I’m always on top of the maintenance part of ownership.

But looks-wise, I’ve no problem and no shame driving around with, not the cute little “Wash Me” message, but the far more serious command of “Wash Your Car” menacingly hand-scrawled on my back windows by some neat-freak.

Evidently, my family could no longer stand the embarrassment either. So on Mother’s Day (yes, last year), they presented me with a gift bucket filled with car wash products. For washing your car, drying your car, waxing your car, buffing your car, deodorizing your car. Yet not even one promise from my kids to help me put these Wash Your Car wonders into use. I looked with hope at my husband who gleefully said, “Waxing your car builds character,” and who also quickly ducked as I threw my new microfiber sponge at him.

Back to this past weekend: I unearthed my 2012 Mother’s Day gift. Prepared to defunk and degunk, my new car wash products were the arsenal at my side.

Mission “Wash Your Car – Waxing Your Car” was officially under way. The hardest part? Convincing myself that I know how to wash a car, and that waxing your car is a cinch. Not an easy feat when one’s past cleaning method didn’t even require car wash products. All I did was:

  1. Take the hose to it
  2. Then drive off

So I headed to the Advance Auto Parts Wash & Wax section of their website. I already had the car wash products. I just needed some tips. After a quick read on how to wash a car, waxing your car and more, my confidence grew. I transformed my old 2-step How To Wash A Car method into this better one:

  1. Wash and dry
  2. Surface prep
  3. Wax and shine
  4. Wheel and tire
  5. Interior

When I was done, it was a beautiful sight. All clean and looking sharp for those couple of days. Next time I get the urge to reach for my car wash products, I’ll be sure to glance at the weather report first.

Editor’s note: Text “Spring” to 36898 for great wash & wax deals now! Up to 5 messages per month; message & data rates may apply.

How to Buy a Used Car the Smart Way: Top 3 Tips

Get quality auto partsLet me tell you a cautionary tale about buying a used car. A good friend of mine just bought a Camry from the mid-1990s. Low mileage, no rust. Legendary Toyota reliability. The asking price was $2,200. Seems like a no-brainer, right?

Unfortunately, that’s exactly how my friend approached the purchase: without really using his brain. He basically bought the car on blind faith, no questions asked. And you know what happened? Two weeks later, the automatic transmission failed. He had to pay almost as much as the purchase price just to get his car back on the road.

Look, the fact is that any used-car purchase is a gamble. You can never be a hundred percent sure what you’re going to get. But if my friend had asked me for used car buying advice, I would have given him the 3 tips discussed below, and they might have saved him a lot of time, money and headaches.

So don’t make the same mistake he did. Heed my tips on how to buy a used car, and minimize the likelihood of bringing home a lemon.

3. Read consumer reviews to learn about common problems

The internet is full of online car reviews written by drivers just like you, and these reviews are an invaluable source of consumer information. Why? Because people love to talk about problems they’ve encountered with their cars. For example, if the used car you’re considering has a trouble-prone transmission, chances are you’ll hear all about it in those reviews. Armed with this knowledge, you can ask better used car questions of the seller, and you’ll also have a better idea of what to look for when you’re inspecting and test-driving the car.

I recommend starting at and looking up the specific year, make and model of the car to access relevant consumer reviews. But don’t just limit yourself to that one year; do additional research to determine the other years in which the car was produced, and check out consumer reviews for those years, too.

2. Run a vehicle history check

There’s really no excuse for not doing this, folks. For only $25 or so, an online vehicle history check tells you if there have been any reported accidents or other damage-causing events (like flooding), and it also tells you if the odometer readings through the years indicate any manipulation.

Will every single issue be reported? No, but the major ones will be, so anything that shows up on one of these reports is a real red flag. I personally recommend buying only cars with clean records: no accidents, no nothing. But if you decide to pursue a vehicle that doesn’t have a clean history, keep in mind that the history report can be a valuable bargaining tool.

The two major online providers of vehicle history reports are and Pick the one you like best and go get that report!

1. Have a knowledgeable mechanic perform a pre-purchase inspection

Most people balk at the $100 fee that mechanics typically charge for this service, but remember the story of my friend and his ill-fated Camry. When you’re faced with something like a $2,000 transmission-replacement bill, you’re really going to regret having skipped this step. Paying a mechanic to inspect a used car before buying is the single most important thing you can do to ensure that you’re not getting a lemon. So grit your teeth and fork over the hundred bucks. I promise you’ll thank me later.

If you’re wondering how to inspect a used car before buying, the key is to find a mechanic who is both knowledgeable about the car you’re looking at and indifferent to whether you buy it or not. So if you’re looking at a Toyota, find yourself a local Toyota mechanic with a good reputation (I recommend reading consumer reviews on, and make sure he’s not a business associate or family friend of whoever’s trying to sell you the car. Also, don’t forget to ask the mechanic to “road test” the car in addition to putting it on a lift in his garage.

Oh, and don’t worry if you want to buy a used car online that’s located across the country—Advance’s Find My Mechanic feature can connect you with someone skilled in used-car inspections. Or, companies like Inspect My Ride let you tap into a nationwide network of inspection specialists.

Anyway, that’s the best used car buying advice I’ve got. Hasn’t let me down yet, and I hope it works for you, too. Good luck!

Editor’s note: Once you do find your new ride, count on Advance Auto Parts for the best in quality auto parts, services and more. Buy online, pick up in store.

How to buy a used car online: buying advice for modern times.

How to buy a used car online: buying advice for modern times.

Not too long ago, when in the market for a secondhand car, you were usually limited to cars located within about a 50-mile radius of your home. Your primary source of information was the classifieds section in your local newspaper.

Used car buyingThat’s changed dramatically. Sure, your local classified ads remain a good source of information about available secondhand cars. But, thanks to the online marketplace for previously owned cars, your potential marketplace now stretches from coast-to-coast.

When considering how to buy a used car online, you need to keep the typical used car questions in mind, along with some specific ones that pertain to buying online.

Here you’ll find practical used car buying advice for online purchases.

Start by scouting what’s available. Some viable sites include:

Also, online bulletin boards sites that contain secondhand car listings (such as Craigslist) can be a good potential source of vehicles, too.

Once you’ve found some candidates:

  • Do some research. Check reliability records for the makes and model years in question.
  • Comparison shop online to find the best prices for your top choices.
  • Get the Kelley Blue Book value for those cars.
  • Order vehicle history reports before buying.
  • Have a mechanic inspect the vehicle. (There are services located throughout the country that will perform this for you if the vehicle isn’t in your area.)
  • Have your financing in place.
  • Negotiate for the best price based on your research (this may not be an option depending on the seller or the site).

Consult trusted sources to find more information about how to buy a used car online.

Sources like AAA, the Better Business Bureau, your state’s attorney general’s site, as well as other government sites may offer more solid used car buying advice, and provide answers to other used car questions.

No matter what, just be sure to get advice from a knowledgeable, impartial source that has your best interests in mind.

Editor’s note: After you buy your secondhand car, take good care of it with quality auto parts from another trusted source: Advance Auto Parts. Keep an eye out here for more info on used cars coming soon.


How to save on gas – a recipe

As mom to a soon-to-be-college-freshman, high-schooler, middle-schooler and twins in elementary, my husband and I are also proud parents of an SUV, minivan and sedan. Like our kids, our cars are constantly on the go: to school, sports practice, supermarket, work, the gym, everywhere. Through years of experience—and Recipe to save gasfrankly, out of bare necessity—I’ve learned how to save money on gas. Essentially, it’s a lot like following a recipe. Gather the best ingredients, follow instructions, and the resulting fuel saving tips will keep gas in your tank longer.

Fuel saving tip #1: Use the tire-pressure gauge to ensure tires are properly inflated for safety and a no-brainer method for how to save on gas.

Fuel saving tip #2: Declare to drive sensibly. Keeping a calm, cool head (not easy when my twin six-year-olds are acting up in the back seat) is preferable to being agitated — and aggressive driving really wastes a lot of fuel.

Fuel saving tip #3: We all love upgrades, from airline seats to cuts of meat at the grocer. Upgrade to synthetic motor oil! It’s made to help boost engine efficiency. Speaking of motor oil and how to save on gas, do oil changes regularly. My other half swears by the traditional every-3K-mile rule. (I do mine,  he does his and we take turns on ours. Unless I’m making his favorite dinner that day!)

Those’re my top-3 observations on how to save on gas. But, I’ve got plenty of other fuel saving tips that I’m happy to share. While many are familiar, they’re good reminders of how to conserve gas and ultimately, get more out of your wallet:

  • Get regular engine tune-ups
  • Get your brakes checked
  • Get that gas cap replaced if it’s loose or worn
  • Get the O2 sensor tested
  • Get a good fuel injector cleaner

I hope my tips to save gas get you to do the same. Though my family and I are good about incorporating public transit whenever possible, that option isn’t always going to work for us. So we rely on our valued modes of transport. We take care of our vehicles, they do the same for us, and knowing how to save money on gas is key in our ability to afford to have them be a vital part of our family.

Did I miss any other tips to save gas? Join me and spread the word.


Editor’s Note: Create your own recipe with these helpful fuel saving tips from Advance Auto Parts and be sure to consider the oil change specials available every day!