How Do I Figure Out the Size of My Tires?

Most of the time, when you are shopping for new tires, the service advisory you are speaking to can pull up your information and easily tell you the size of the tires on your car. Unless you are an enthusiast or buy your tires online, you probably haven’t given tire size much thought. That being said, you may run into a situation, like getting a flat, where you need to know your tire size. Finding this information is easy as long as you know where to look and what to look for. In this guide, we are going to tell you how to figure out the size of your tires quickly and easily when they are on your car!

Where Can I Find My Tire Size?

Sizing information is found on the sidewall of your tire. It will be presented as a series of numbers and letters, typically presented in the following format: P235/45R 17. You may see another number and letter combination after this, which represents the tire speed and load rating that we cover in a separate article.

How Do I Read Tire Sizing?

Providing this number to a professional will be all the information they need to find the right tires for your car. You don’t need to know what each number means, but if you are curious, keep reading and we will cover what these numbers mean next.

How are Tires Sized?

Tire sizing is split into three categories, each describing a different part of the tire’s dimensions. The categories are width, aspect ratio (A/R), and wheel diameter. We are going to break down what each category stands for below.

Tire Width

The first number is the width of the tread, which is the part of the tire that contacts the road. In the above example size, “235” means that the tire has a width of 235 millimeters.

Tire Aspect Ratio (A/R)

The second number represents the aspect ratio or the height of the sidewall. The sidewall is measured as a percentage of the tread width. In the above example, the number 35 after the slash means the tire’s sidewall height is 35% of the tread width. A lower aspect ratio correlates with a lower profile tire.

Wheel Diameter

The final number in the sequence represents the diameter of the wheel the tire is mounted on in inches. In the above example tire, the 17 indicates the tire fits on a 17-inch wheel.

What Do the Letters Mean?

You probably noticed the letters mixed into the size numbers. The first letter represents tire type, and the second number indicates the construction.

Tire Type

The very first letter(s) in the tire sizing represents the intended market and vehicle type for the tire. In the above example, P stands for P-Metric, which means the tire meets passenger car standards in the United States.

If you see “LT”, the tire is intended for use on light trucks and will often have higher pressure requirements than P-rated tires.

If a size rating has no starting letter, it is a European Metric tire. There are some differences in load capacity between European and P-Metric tires.

Tire Construction

Unless you are dealing with trailer tires, you will almost only see an “R”, which stands for radial construction. This article goes over the other types of tire construction out there.

Matson Point S is Your Source for Tires!

Our tire shop in Riverton is ready to help you with your next tire purchase, no matter the size! In addition to tires, we offer full-service auto repair and maintenance. Whatever your automotive needs, the team at Matson Point S will keep you moving. Call or schedule an appointment online today!


How Do I Change a Flat Tire? [14 Steps]

There are few things worse than a flat tire. Getting a flat is something nearly everyone who drives has experienced and knowing how to change it is an essential skill for any driver. Changing a flat tire may sound simple and to some people who have done it before, it is. Fear not, even if you haven’t changed a flat before, it’s a very easy job that just about anyone can do. That being said, some steps need to be followed to keep you safe while doing it.

In this article, we are going to go over how to change a flat tire safely, so you have the know-how next time it happens to you!

Tools Needed For Changing a Flat

To change a flat tire, you will need at a minimum a jack, your spare tire, a lug wrench, and your owner’s manual. Nearly all vehicles come with these items. Spare tires can be found under the carpet in the trunk, hanging on the back, or bolted to the underside of your vehicle. The wrench and jack will typically be stored in the trunk or rear of the car as well. You can find your owner’s manual in the glove box.

Tools for Changing a Flat

Other Useful Items

In addition to the tools listed above, there are a few other things that can make changing a flat tire easier.

  • Poncho or raincoat for working in bad weather
  • A tarp to kneel on while changing the flat
  • A block of wood to secure the jack
  • Flashlight for working in the dark
  • Gloves
  • Wheel Chocks

None of these items are needed for changing a flat, but they will make the job a lot easier, especially if you are working at night, in the cold, or the rain or snow.

It’s a good idea to make sure you have all the required tools in your car at all times. If you bought a used car, make sure to check that at a minimum, there is a spare tire, a jack, and a lug wrench. Without these items, you will not be able to change a flat tire.

How To Change a Flat Tire

Follow these steps to safely change your flat tire and get back on the road!

1.) Find a Safe Parking Place

If you wake up to a flat tire in your driveway, this isn’t a huge concern. If you suddenly get a flat while driving, especially on a highway or interstate, it can be difficult to find a safe place to pull over. Ideally, find a pull-off, parking lot, or rest area where you can get away from traffic. Remember, you will be on the ground when changing your flat. Being right next to speed traffic is extremely dangerous.

In addition to moving away from the road, make sure you park in a flat area. Ideally, you should change your flat on a paved surface to prevent the jack from shifting.

2.) Secure Your Vehicle

Before getting out of your car, engage the E-Brake, and put the transmission in park (automatic) or reverse (stick shift). You do not want your car to move when has been lifted on the jack. If you have them, placing wheel chocks behind the wheels touching the ground will add an extra layer of security while you change the tire. Turn on your hazard lights to let other drivers know they should slow down.

3.) How to Remove a Flat Tire

Now that you have your tools ready and your car is safely secured, you need to remove the flat tire before putting the spare on. Follow these steps to get the flat off your car safely. Just to clarify, you will be removing the entire wheel and tire.

4.) Uncover and Locate the Lug Nuts

Some vehicles have hubcaps covering the lug nuts, and some do not. If you have hub caps, carefully remove them. A flat head screwdriver can come in handy for removing hubcaps.

5.) Loosen the Lug Nuts

Before jacking up the vehicle, loosen the lug nuts with your wrench. It can be difficult to break them loose. If you are having trouble, you can use your bodyweight or foot to apply extra pressure. At this point, you just want to break them loose. Don’t worry about removing them yet.

6.) Position the Jack Under the Car

Place the jack on a stable, flat surface. If you have to change a flat on a dirt road, placing a block of wood under the jack can help secure it. Most cars have specific lift points along with the frame for the jack. Reference your service manual if you are having trouble locating the jack points.

7.) Jack the Car Up

Carefully, begin to jack up the car. DO NOT put any part of your body beneath the car when it is jacked up. Jack the vehicle up until the flat tire is six inches off the ground. Having at least six inches of clearance will ensure the spare tire, which will be fully inflated, clears the ground when you put it on.

8.) Remove the Lugs

Depending on your vehicle, the wheel will be attached with either lug nuts or lug bolts. Lug nuts unscrew from studs that support the wheel, while lug bolts pass through the wheel into the hub. If you have lug bolts, be careful when removing them, the tire can drop suddenly when the last one comes out.

9.) Take the Flat Tire Off

With the lugs removed, it’s time to take the flat tire off. The easiest way to do this is to grip the tread and slowly pull out. If the wheel is stuck to the hub, wiggling from side to side can help break it loose. Once it’s off, lay the wheel flat on the ground so it doesn’t roll away.

10.) Install the Spare Tire

Now that the flat has been removed, it’s time to put the spare on! If your car uses lug nuts and studs, simply slide the spare into place and hand tighten the nuts.

 If you have lug bolts, it can be a bit tricky to get the spare on. Line the bolt holes up with the holes in the hub and carefully thread one of the bolts to hold it in place. Next, thread a bolt on the opposite side so the wheel sits flush with the hub. Now that it’s in place, you can thread the other bolts to hand tight.

11.) Return the Car to the Ground and Tighten the Lugs

With the lug’s hand tightened, slowly lower the vehicle on the jack until all four wheels are on the ground, but the spare is not supporting the weight on its own. Grab your wrench again and tighten the lug clockwise as far as you can go.

12.) Lower the Vehicle Entirely and Remove the Jack

Lower the vehicle to the ground and remove the jack. Give the lugs a final tightening to make sure they are as tight as they can be. Replace the hubcap (if applicable on the spare).

13.) Store Tools and Flat Tire

Return the tools to their storage locations within your car and put your flat tire where you found the spare.

14.) Check Spare Tread and Pressure

Once the spare is on the car, check the tire pressure with a hand-held gauge or at a nearby gas station. Additionally, make sure there is adequate tread on the spare.

You’re done! Now you can drive to a tire shop and get a new tire or have the flat repaired.

Types of Spare Tire and Driving Safety 

Depending on what type of spare tire your vehicle has, you may need to adjust your driving. A lot of modern vehicles come with very skinny, lightweight spare tires called “donuts”. This type of spare is only good for around 50 MPH and a limited number of miles. The wheel and tire itself will have warnings on them if you need to drive slower.

If you have a full-sized spare, you can generally drive normally. Keep in mind, if you have an all-wheel-drive vehicle and your spare has significantly more or less tread than the other tires, you can cause damage to the drivetrain over time.

Tire Repair and Replacement at Matson Point S

Knowing how to change a flat tire is an important skill to have, but you will still need a professional to fix your flat or replace it together. Matson Point S is your source for all things tires. Our Riverton repair shop provides Salt Lake Valley with auto repair, tires, marine service, and more. If you need a tire replacement or flat repair, don’t hesitate to give us a call or schedule an appointment online today!

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