Key Tyre Facts
Those 4 black rubber tyres that we spend much of our lives on are often taken for granted with almost no knowledge of how they are manufactured or disposed of. The quality of these tyres will depend on your fuel consumption, how well you corner and of course, grip, especially in wet weather and could and often will save drivers lives.
Anyone who watches and follows motor sport will know how critical tyre choice can be to winning races, what is less accepted, is that the same rules apply to the typical daily transport.
Are You Legal?
One of the most critical factors is tread depth. There are laws that define how deep the tread should be, within the UK for instance it must be at least 2mm, covering the whole width of the tyre. The tread is the part that disperses water from under the surface of the tyre giving grip whilst driving. Not having any tread would cause aquaplaning, a bit like a flat board skimming across a narrow stream.
Radial and Cross Ply
The difference between the 2 types of tyre is how they are made. The radial tyre is constructed using steel cord that is applied over its heel. These cords are placed on top of each other. Cross Ply tyres use carcass layers that cross each other. Radial tyres absorb the bumps on the road better and have better fuel consumption. However cross ply tyres are stronger, and make driving more stable, but will increase fuel consumption.
Low Profile Tyres
Normally fitted to performance models with sporty wheels. They help with cornering, better grip and braking, but these advantages only come into play at higher speeds. The proportion of the tyre gives a larger contact with the road surface. The disadvantages with its stiffer construction are a harder ride and more road noise. Tread depth is often less, so may wear out quicker, especially when being driven hard. However there is no denying that low profile tyres can make your ride look better and cooler.
Run Flat Tyres
Preferred by manufacturers like BMW, these are made with stronger walls so the driver can still get the vehicle home should a puncture occur. Typically more expensive than typical tyres and may void warranties in some instances. Although much debate about insurance responsibility, there is no evidence an insurance policy would be void if run flat tyres were swapped with traditional ones. Some suggest more over steer when typical run flats are exchanged, many find this driving style more exciting, others more dangerous.
It should be obvious by mow that the typical tyre is not just made from molded rubber., there is a pretty complicated design of steel bead wires that hold the construction together, then casing ply and of course the made tread designed to give grip and disperse water. The design on the tread contributes to the balance of grip and speed. Most manufacturers invest huge sums of money to design the most efficient and safe tyres.
What does the Tyre Codes mean?
When ordering replacement tyres it is important to understand what the coding, often printed on the size means, so that the correct replacements can be bought.
An example is 225/45R17
- The 225 is in mm and stands for the width of the tread
- The 45 stands for the “aspect ratio” , this reflects how tall its wall is.
- The “R” stands for Radial
- The 17 stands for the size of the rim, which confusingly is in inches
- There are other markings such as load rating and speed
- Typical load rating can go from 62 to 83, which reflects 265kg to 487kg respectively
- Typical Speed rating run from N To T 91 to 118 miles per hour respectively
Unlike run flat tyres it may affect your insurance policy should under performance tyres be fitted.
Sometimes in order to cut costs you can buy remoulds. This is where the frame of the tyre is re-used but a fresh rubber re-tread is added. Sometimes this may be false economy and not recommended for performance cars.
Recycling and Disposing of Old Used Tyres
The good news is, that when a tyre comes to the end of its life, they can be recycled and used in other manufacturing from tarmac to shoes soles. In order to get the rubber to a point where it can be reused, there are several steps.
- Steel Fraction
By using heavy machinery to refine the rubber and steel, a produce is left that can be used in the manufacture of other.
The bad news is the overall quantity of tyres being discarded, so many find there way into land fill, especially in third world countries, where there laws for such are very relaxed.
Most breaker yards in the UK will try to sell on legal tyres to avoid the cost of disposal. Illegal tyres, have to be disposed of legally at the cost of the treatment centre.