Tyres are fascinating not because they roll but for the amount of beating they go through every day without bursting. The bloke who made this possible was Robert William Johnson who invented and patented the first pneumatic tyre in 1845. A year before that in 1844, Charles Goodyear found and patented a process known as vulcanization.
In short, vulcanisation is the process of removing Sulphur from the rubber compound to make them waterproof and winter proof and allowing them to retain their elasticity at the same time. Though, tyres invented by Robert William Johnson were too expensive to manufacture back then. John Boyd Dunlop in 1888 was an inventor of the first practical tyre – a pneumatic inflatable tyre. But he had invented it for a use on bicycles back then and not for cars. But he was the one who laid the basic foundation for the development of tyres in future.
From then till now, it is fascinating to see how much tyres have developed over the years and their usage, life – wear and tear and compounds. Tyres today last for thousands of kilometres before they need to be replaced. And in the lifetime, they go through tough working conditions as well.
So, just recently I had tyres on my car changed. I went to the tyre shop and I was baffled at the number of tyre companies I could make a choice from. Today, one can simply go to a tyre shop and get their car’s tyres replaced without much of an effort. But it is equally interesting to understand why a particular tyre is desirable for your car. Have you ever paid close attention to those various alphabets and numbers written on your tyre? Well, each one of them has a detailed meaning.
I am simply going to be touching upon car tyres and not any other modes of transport. So if you are a truck or a bus driver and reading this, this article should end for you here. But if you are interested in getting to know something useful, then continue reading.
Tyres are of two types – Tube and Tubeless tyres. Tyres with tubes were the first one to be introduced. But it had some obvious disadvantages ranging from maintenance, stability, cost & friction. A tubeless tyre, on the other hand, is a tyre without the tube inside. The tyre can contain air in itself. A layer of chloro-butyl lining (I wasn’t very bright in chemistry, so expect no fancy formula here) between rim and tyre helps in containing the air inside. The elimination of tube also has some obvious benefits. Mainly helping in
- Reducing friction between tyre and tube, since the tube is eliminated.
- Improved fuel efficiency and lesser rolling resistance.
- Fewer vibrations & better comfort.
- Lower wheel weight reducing un-sprung mass.
- In case of penetration of a nail or a sharp object, the air loss is not sudden. This increases safety as it reduces the chances of tyre bursts.
Here is an example of a car tyre with different markings on it.
A tyre has following markings –
- Aspect Ratio
- Rim Diameter
- Load Index (Load Rating)
- Speed Symbol (Speed Rating)
Width is the amount of contact a tyre makes with the road.
Aspect Ratio –
Aspect Ratio is of section height to section width.
There are two types of tyres – Radial and Bias. A radial tyre is the most commonly used tyres for road cars these days. The difference between the two is the way they are constructed, having different ways of a layered arrangement on top of each other. There are a lot of advantages of radial tyres. Few to mention are –
- They have a longer life as a result of lesser tread squirming and shuffling.
- They reduce rolling resistance which helps in increasing the fuel economy.
- Lesser edgewise bending leading to better stability and traction, in turn leading to better high-speed performance.
- Improved vehicle handling.
- Improved Braking & Cornering
Rim Diameter –
Whilst a rim is mounted on the hub, the tyre is mounted on the rim. It’s also a tyre’s inner diameter. Changing the size of a rim can impact the performance of the car in positive and negative ways.
Load Index (Load Rating) –
Different tyres come with a different load capacity. The value on a tyre indicates how much load a tyre can be subjected to. A chart below shows maximum load of a tyre against various load index values.
Speed Symbol (Speed Rating) –
Speed Symbol (Speed Rating) is the maximum speed for the tyre at full load. It is indicated by an Alphabet after Load Index. The table below shows the different speed ratings and its corresponding speed limits.
With these basics in mind, you can easily figure out what tyre does your car need to be fitted. Always make sure to put the right size of tyres and all from the same manufacturer. If you still need help in understanding the topic better, you can always email me your queries and I shall be more than glad to help you.
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