Tires are supportive structures attached to the rims of wheels. They are made up of composite materials, rubber, and polymers. Wheels provide strength and support. It is like a muscle-bone relationship. Parts of the wheel include the car rim, lips, and more.

Till we have perfected hover technology, cars, trucks, and planes would be useless without tires and wheels. This is a guide on car wheels and tires.

How to measure wheel size?

Knowing your wheel size is important for many things. Do you want to replace them, do you think good wheels look cool? No matter your reason, you are in the right place. 

The good thing is, it is super easy to know the size of your wheels. A simple solution is to look at your vehicle owner’s manual. You should find all the information you need. Many new models include this information on the driver’s door.

If you can’t find the manual, you can still get the size of your wheels with the information provided on your original equipment (OE) tire. This is also known as the stock tire. You will find the DOT code on the sidewall of your tire. 

Tyre Speed Rating Chart South Africa | Tiger Wheel & Tyre

It is an alphanumeric code. For example, if you find this as your code P205/55R16 90S you can determine the wheel dimensions, aspect ratio, and other useful information.

The first letter(s) stand for the vehicle type. P, LT T, and ST stand for passenger, light truck, temporary, and special tires respectively.

The first 3 digits represent the car rim size. The width is measure in millimeters. You can convert this to inches by 25.4 to get the figure in inches.

The second set of digits represent the aspect ratio. The aspect ratio is the ratio of the sidewall height to the wheel width. It is expressed in percentage.

The letter next to it represents the arrangement of the ply cord used internally. R and D stand for Radial, and Diagonal arrangement.

The next digit represents the wheel diameter. So in our example above shows that the wheel diameter. This shows the tires have 16-inch rims. 

The last number and letter represent the load index and the speed rating.

What tires fit my car?

There are a lot of wheel designs and sizes. Who wouldn’t love how deep dish wheels look?

You have been asking yourself what size tires do I need? Before we answer the question, there are more things you need to know.

car tires types

Changing your car wheels and tires with specifications other than the original will have some effects on your vehicle. Depending on what you change, it will affect the handling, fuel consumption, performance, speedometer and odometer readings, and breaking.

Some of these changes may improve your overall driving experience. You may want wide tires and rims for better grip and handling. As long as you consider the offset and clearance, you can increase the rim and tire width. 

If you want cooler wheels with larger diameters, you should subtract the same extra length from the tire height to give a low profile tire. This is called plus sizing. For example, if you decide to change from 17-inch tires to 18-inch tires, the sidewall height must be reduced.

Knowing the right tire pressure.

The pressure of your tires is very crucial, not just for a smooth riding experience but for safety. Maintaining the right tire pressure also improves your mileage and reduces wear and tear.

What does psi stand for? Psi stands for pounds per square inch. Hence the abbreviation psi. We bet you must have heard it before. Psi is a unit for measuring pressure. We can’t talk about car tires without talking about tire pressure. 

When tires are spinning, their pressure increases because of friction heat. When not in use, the gases inside the tires are cooling and return it to an equilibrium state. 

When you measure the pressure with a tire pressure gage, you get the cold pressure. You get a consistent, and accurate pressure value when the car wheel isn’t rotating.

Using a tire air pump to inflate your tire to the maximum pressure listed on the sidewall is a terrible idea. The pressure at this level is not good for the tires and unsafe for driving. The good value for your tire pressure is 75% of the maximum value.

How long should tires last?

Tires get worn out when their tread depth reaches 2/32 of an inch. So, how long should they last?.

The average car tire lasts for about 60,000 – 75,000 miles. 

Some manufacturers offer extended periods of life. High-performance tires offer about half the life regular tires do. You should know that the average American drives 14,000-15,000 miles a year. With these figures, your tires should last you about 4-6 years. 

When to replace tires?

good and bad car tires

 You may need to change your tires independent of their age or mileage covered. Many things can affect the life of a tire. As time goes by, components in a tire begin to deteriorate. This slowly compromises the quality. We recommend changing your tires if they are older than six years. 

The weather, your route, and the way you drive will affect the tire lifespan even when you haven’t surpassed the stipulated mileage. High temperatures cause over-inflation and low temperatures cause under-inflation which leads to low tire pressure. Like all things, you need to have proper tires maintenance culture.

How often should I rotate tires?

The front tires on most cars tend to wear out faster than the rear tires, even on four-wheel drives. This is because of the load they bear, being closer to the engine in front. They also undergo more stress during steering and braking.

Tire rotation is the maintenance practice of repositioning the tires on your car to ensure uniform wear.  

If you buy a pair of new tires you can swap them for the rear tires and put the original rear tires in front. There are advantages to this. You should rotate your tires every 5000 miles. 

Before you rotate your tires, there are things you need to know about your tires. There are directional, symmetric, and asymmetrical tires.


Your car tires and wheels support your car and keep it moving. They play a crucial role, and keeping them in good condition is no easy feat. It involves changing your tires at the right time, knowing the right tires and rims size. You must also know the appropriate tire pressure and when to rotate your wheels.

Having all this knowledge will keep your tires in optimal condition for a long time.

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