Many people take their car tyres for granted, but there's far more to them than meets the eye. Knowing how they are made will illustrate this point.
How is a car tyre made? Production starts with a halobutyl rubber sheet that has special air-retaining additives. This sheet forms the tyre's inner liner. A three-layer body ply comes next, in which a central layer of reinforcing fabric is sandwiched between two layers of rubber. Cotton used to be the material of choice for the reinforcing fabric but this has been replaced with Nylon, Rayon, polyester or even Kevlar. The body ply's role is to give the tyre strength and flexibility; two such plies may be used in a tyre.
The acceptable faces of the tyre, the sidewalls, include antiozonants and antioxidants to enhance their life. The sidewalls can resist chemical attack and abrasion, and the tyre's ratings and size codes are moulded into them.
Of course, the tyre's sidewalls need to form a seal on the wheel rim. Bands of high tensile steel wire, copper or brass coated for corrosion resistance, form the beads on the inner diameter of the sidewalls. The triangular rubber section that joins the beads to the sidewalls is called the apex. The bead structure is what forms an airtight seal with the wheel rim.
Now for the tread and its underlying structure. The belt package is the part of the tyre that sits inside the tread. It's made up of two layers of rubber that enclose a layer of steel cords. These cords run radially in the belt package, hence the term 'radial tyres'. The belt package is a major player in the tyre's strength. The tread pattern is visible but the rubber compound used to make it is just as important. The choice of compound is a matter of a selecting a balance, between hardness (wear) and (grip). Think 'compromise'.
These are the parts of a tyre and they must obviously be assembled and made into a tough, resilient structure. This procedure begins with wrapping the inner liner, body ply(s), sidewalls and beads around a special drum. Then, the belt package and tread are added, and the various elements are spliced together. At this stage the tyre is yet to be cured, and is known as a 'green' tyre. In this state, it is inflated and shaped.
Curing comes next, to bond the various parts of the tyre into a coherent whole. A rubber bladder is inflated inside the tyre, forcing it into a mould. Hot water, steam or an inert gas is used to inflate this bladder, and the curing process involves a great deal of heat and pressure…350 degrees Fahrenheit and 350 pounds per square inch to be precise. The curing process takes about 15 minutes.
The final stage is to test the cured tyre on a mock road surface, to seek out localized inflexibility and significant imbalances. Every tyre is given a visual inspection and sometimes, an X-ray inspection too.
So, car tyres are built tough to be tough, which they must be to take on the tough job they do. As they are all that keep your car on the road, it's reassuring to know how much effort and care go into making them.
Article Resource
Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.
Wednesday 14 September 2011
Top Tyre Tech: Facts About Formula One Car Tyres
Formula One teams spend vast amounts on research and development. They spend on aerodynamics, on construction with composite materials, and on wringing the maximum amount of power from their engines. We must, however, remember that in Formula One, tyres remain the largest single performance variable.
So, car tyres are car tyres, right? Not quite; road car and racing car tyres are distant relatives at best. Road car tyres are made to last, typically for a life of 16,000 kilometres or more. Formula One car tyres are made to last 200 kilometres at most, but they are made to be both light and strong. Their internal nylon and polyester structure, with its complicated weave pattern, is designed to handle much greater forces than a road car tyre faces. Let's put it this way, no road car is likely to generate a tonne of downforce, or 5g of longitudinal load…or 4g lateral loadings.
F1 car tyres' soft rubber mix is there to offer maximum grip, at the cost of a limited life. The tyres wear very quickly. They also become very hot but this is meant to happen – cold race tyres offer little grip. By way of example, the dry grooved tyres used until recently were designed to run at between 90 and 100 degrees Centigrade. Look carefully at the TV footage and you'll see the cars' tyres, pre-race, clad in special coverings, which are electrically heated. The need for heat explains why Formula One cars can be seen weaving from side to side on the way to the starting grid. The drivers are perfectly sober and they aren't playing – they're just warming their tyres.
Slick tyres, those with no tread at all, offer maximum grip. However, it was decided in 1998 that slicks be outlawed. Grooved tyres were made de rigeur, to help improve F1 racing as a spectator sport by reducing cornering speeds. This made life difficult for the tyre makers. The rules specified that all tyres had to have four continuous grooves at least 2.5 millimetres deep, spaced 50 millimetres apart. So, tyre manufacturers had to adopt harder rubber compounds, to maintain tyre integrity. By the 2009 season, slick tyres came back. The FIA, Formula One's governing body, decided to use limits on F1 car aerodynamics as a means of keeping cornering speeds down.
How 'soft' or 'hard' the rubber compounds in F1 car tyres are, is varied by race, according to each track's characteristics. For each Grand Prix race weekend, teams choose from two different compounds, and every driver must use both during the race. What makes the difference in the hardness of the different specifications? A change in the proportions of ingredients added to the rubber mix. Of these ingredients, the three main ones are sulphur, carbon and oil. In general, more oil equals a softer tyre compound.
Formula One car tyres are obviously run at the appropriate pressures. However, air pressure isn't quite the right term. F1 car tyres are inflated with more nitrogen gas than air. This gas and air mixture is less susceptible to pressure loss and minimises the pressure differences that come about through temperature changes.
As will have become clear by now, there are huge differences between road car tyres and Formula One car tyres. They may share basic characteristics but the common denominators between them are certainly low on the scale.
Article Resource
Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.
So, car tyres are car tyres, right? Not quite; road car and racing car tyres are distant relatives at best. Road car tyres are made to last, typically for a life of 16,000 kilometres or more. Formula One car tyres are made to last 200 kilometres at most, but they are made to be both light and strong. Their internal nylon and polyester structure, with its complicated weave pattern, is designed to handle much greater forces than a road car tyre faces. Let's put it this way, no road car is likely to generate a tonne of downforce, or 5g of longitudinal load…or 4g lateral loadings.
F1 car tyres' soft rubber mix is there to offer maximum grip, at the cost of a limited life. The tyres wear very quickly. They also become very hot but this is meant to happen – cold race tyres offer little grip. By way of example, the dry grooved tyres used until recently were designed to run at between 90 and 100 degrees Centigrade. Look carefully at the TV footage and you'll see the cars' tyres, pre-race, clad in special coverings, which are electrically heated. The need for heat explains why Formula One cars can be seen weaving from side to side on the way to the starting grid. The drivers are perfectly sober and they aren't playing – they're just warming their tyres.
Slick tyres, those with no tread at all, offer maximum grip. However, it was decided in 1998 that slicks be outlawed. Grooved tyres were made de rigeur, to help improve F1 racing as a spectator sport by reducing cornering speeds. This made life difficult for the tyre makers. The rules specified that all tyres had to have four continuous grooves at least 2.5 millimetres deep, spaced 50 millimetres apart. So, tyre manufacturers had to adopt harder rubber compounds, to maintain tyre integrity. By the 2009 season, slick tyres came back. The FIA, Formula One's governing body, decided to use limits on F1 car aerodynamics as a means of keeping cornering speeds down.
How 'soft' or 'hard' the rubber compounds in F1 car tyres are, is varied by race, according to each track's characteristics. For each Grand Prix race weekend, teams choose from two different compounds, and every driver must use both during the race. What makes the difference in the hardness of the different specifications? A change in the proportions of ingredients added to the rubber mix. Of these ingredients, the three main ones are sulphur, carbon and oil. In general, more oil equals a softer tyre compound.
Formula One car tyres are obviously run at the appropriate pressures. However, air pressure isn't quite the right term. F1 car tyres are inflated with more nitrogen gas than air. This gas and air mixture is less susceptible to pressure loss and minimises the pressure differences that come about through temperature changes.
As will have become clear by now, there are huge differences between road car tyres and Formula One car tyres. They may share basic characteristics but the common denominators between them are certainly low on the scale.
Article Resource
Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.
Subscribe to:
Posts (Atom)