An Amateur Mechanics Guide to Buying Car Tyres

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An Amateur Mechanic's Guide to Buying Car Tyres

An important safety feature on every car that may not be completely obvious are the tyres. The tyres meet the road and keep the car moving. Since tyres are so important, they are a necessity that can not be put off when something goes wrong with them. Flat tyres, caused by running over nails or glass, and tyres that are worn down, are both cases in which tyres need to be replaced. Buying new tyres can be a hefty expense that one has not budgeted for.

It is not always possible for buyers to know and trust the person from whom they are purchasing the tyres. Therefore, for the amateur mechanic, it is important to have as much knowledge as possible before deciding from whom and where to purchase tyres. Some things that are helpful to know before making a decision are the tyre basics, what to look for in a new tyre, tyre tread types, and what the different speed ratings for tyres mean. Becoming fluent in all thing regarding tyres is a great first step in purchasing new tyres.

Tyre Basics

Without tyres, a car could not move. The major movements a driver directs the car to do, through the steering wheel, the engine, the gas pedal, and the brakes, are all executed by the tyres. The tyres handle the car's load, all while propelling the car forward, backward, side-to-side, and making the car stop. This is a very important job, and understanding the basics of a tyre helps to make it easier to buy tyres.

There are 19 to 25 different components that go into a single container of compressed air, known as the tyre. To begin with, a tyre has an inner liner that helps to hold shape and hold in air. Secondly, this inner liner is wrapped with fabric belts, the bottoms of which are fastened to beads that keep the tyre and wheel together. Steel belts go on top of the the fabric belts, and these have two different jobs. They give the tyre stability and also help to keep the tread pattern as flat as possible.

It is good for tread to be as flat as it can be, because the flatter the tread, the more contact the tyre has with the road. The tread is directly on top of the the fabric and steel belts. Different tyres have different tread patterns. The last part of a tyre is the sidewall or side of the tyre. This sidewall gives the tyre its stiffness and ride characteristics. The taller and softer the sidewall, the more it absorbs bumps, while the shorter and stiffer the sidewall, the better cornering ability and sharper steering response.

Tyre Tread

The tread of the tyre is more important that the average buyer might think. For example, one true sign that it is time for new tyres is that the tread is worn down. The less space there is from the top of the tread to the inner fabric and steel belts layer, the balder the tyre. Not only is the amount of tread something to be aware of, but it is also good to know that different patterns of tread mean different things and are used for different purposes. Below are several pattern types and their uses.

Symmetric Tread

A symmetric tyre pattern is the most common tread found on tyres. This pattern has continuous ribs or independent tread blocks across the whole tread face. Both the inboard and the outboard halves of the tyre have identical patterns.

Asymmetric Tread

Asymmetric tyre patterns change across the face of the tyre. In order to increase cornering stability on dry roads, this pattern has a larger contact area and larger tread blocks on the outboard side of the tyre. There are small independent tread blocks on the inboard side in order to help with wet conditions or winter traction. This type of pattern also helps to reduce tread squirm (flexibility of the tread between the surface of the tread and the base of the tyre) and heat buildup on the outside shoulder of the tyre.

Directional Tread

A directional tread pattern is designed to roll in only one direction. This pattern has v-shaped tread blocks, as there are lateral grooves on both sides of the centreline. These lateral grooves point in the same direction, creating the v-shaped blocks. This pattern helps to prevent hydroplaning, as it pumps water through the tread better than other tread patterns. Tyres with this type of pattern are only meant to be used on one side of the vehicle and are rotated from the front axle to the rear axle.

Asymmetric and Directional Tread

Asymmetric and directional tread patterns also have v-shaped tread grooves, but are offset compared to the centreline of the tyre. This type of pattern is treated the same as a direction tyre when it comes to tyre rotation.

Choosing the Right Tyre

There are several things to consider when purchasing a replacement tyre. One of the biggest mistakes is choosing the incorrect size for the vehicle being driven. Luckily, every tyre has a code that is found on the sidewall of the tyre. This code includes information on the size and capabilities of the tyre. There are eight pieces of information included within the capabilities code of the tyre. All eight play important roles in choosing which type of tyre to purchase. The table below outlines the different codes and their meanings.

Tyre Code

Tyre Code Meaning

Tyre Code Example

Tyre Type

Different vehicles including trucks, passenger, and off-road vehicles.

Letters: P = Passenger

Tyre Width

Tyre width is provided in millimetres with a standard type of measurement, 25.4 millimetres being equal to one inch. Proper width ensures efficient handling and fuel efficiency.

Numerical: 195

Aspect Ratio

Used to represent the tyre's height in the mount in the direction of the tread. It is provided as a ratio related to the width of a tyre.

Numerical: 60


The tyre's construction type is extremely important for meeting particular needs.

Letters: R = Radial

Rim Diameter

Diameter refers to the size of the wheel. It is essential that the tyres be identical in diameter to the vehicle's wheels. The diameter of the rim is represented in inches.

Numerical: 16

Tyre's speed

Determined through lab testing, by pressing a tyre at its appropriate load against a large, high-speed metal drum.

Letters: M = 81 MPH/130 KPH

Performance Rating

Indicates the type of weather or season that the tyres are best suited for.

Letters: M+S = All Season driving

Knowing the meaning of the code on a tyre, and the code that works best for a specific car, helps in making the right purchase. If a tyre is purchased that is not the right fit for a car, money is wasted and performance of the vehicle is not at its best.

The speed of a tyre is represented in miles per hour or kilometres per hour. The chart below outlines the different codes, as well as what the letter represents in miles per hour and kilometres per hour.



























These rankings are only reliable with it comes to tyres that have not changed in any significant way, are not broken, are not overloaded, and are correctly inflated. A tyre loses its initial speed rating once it has been fixed because of a puncture or other damage. Though speed ranking does not indicate tyre handling capabilities, a greater tyre speed rating may help the tyre to have other handling qualities.

New vs. Used Tyres

Convenience and affordability are both things to consider when purchasing tyres for a vehicle. In this regard, it is relevant to consider the differences between a new tyre and a used tyre. Purchasing a used tyre is often thought to save money, but this is only true if the tyre will perform well and will last for a reasonably long time. Knowing how worn the tread of the tyre is, and what defects the tyre may have, is important to ensure that the tyre is safe. Purchasing a tyre that has been patched or plugged is not safe and is not recommended. Issues may not even be noticeable in a used tyre until the tyre is on the vehicle.

Though buying used tyres may initially save money, a used tyre does not allow the vehicle to be stopped as fast, and is more likely to skid on wet surfaces. The best option is to purchase new tyres, as they generally come with some type of guarantee or warranty. Buying new tyres provides some certainty that the tyres are safe.

Buying Car Tyres on eBay

There are a number of places from which you can purchase a tyre. It may be difficult, however, to find someone that you trust to help you to make the right decision about buying new tyres. Having a knowledge base is helpful in making an informed decision. eBay has an extensive collection of tyres to choose from. Though there are a number of easy ways to search for the item you want, a simple way of starting your search is to type the product description in the search bar on the eBay homepage. Once your search results populate, you can then narrow them down through the categories to find exactly what you want. When you find a tyre or tyres that interest you, you may want to contact the seller with questions about the tyres or about delivery options.

A great resource that eBay provides for its users is a seller feedback option. Buyers can rate the seller that they purchase from by just clicking and choosing the sellers' deserved rating and then leaving a comment, if desired. It is not only beneficial for new customers, but it is also beneficial for sellers to learn how their service may be improved.


Most drivers do not know enough about tyres to make an educated purchase. Most decisions are made based on price and availability. The tyres on a car are very important, not only impacting the driver and passengers of the car, but also those cars and passengers that travel on the same roads. Therefore, having a good knowledge base is of the utmost importance when making a purchase decision. Being informed on tyre basics, including the different tyre tread types, speed ratings, and tyre codes, makes it easier to ensure that the tyre is suitable for the vehicle it is being purchased for.

When considering tyres, though money is at times an issue, cutting corners is not always the safest bet. It is a better decision to purchase a new tyre over a used tyre. A used tyre is not guaranteed to be safe, and the buyer may be put in the position of having to replace the tyre sooner than expected and spending more money in the long run. Safety should always be a priority when purchasing tyres.

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