F1 Wheel Rims27/08/2009

F1 Tyres Need F1 Wheel Rims!

A tyre, even a Bridgestone Potenza Formula One tyre, cannot do its job by itself. It needs a wheel rim to hold and help shape it, and attach it to the car. And, whilst they may look like a simple piece in the technological jigsaw that makes up a Formula One car, wheel rims are a highly complex topic.

“A wheel rim has a difficult job to do, and in Formula One the requirements for it are very exacting,” explains Hirohide Hamashima, Director of Bridgestone Motorsport Tyre Development.

“The rim is the connection point between the tyre, which is the only part of the car to make contact with the road, and the chassis itself. Without a rim you could not bolt a tyre to the car, as even if the rubber was moulded to allow it, the consistency of rubber would not provide a good solution.”

Bridgestone Works Closely With Leading Wheel Rim Suppliers

Whilst Bridgestone produces all of the tyres used in Formula One, the wheel rims are made for the teams by a number of suppliers.

“We are lucky to work with some of the world’s premier automotive wheel producers such as Avus, BBS, Enkei, OZ Racing and Rays,” says Hamashima.

“Each of these manufacturers has their own design of wheel rim and approach the challenge of making an F1 tyre rim in a slightly different way so there are subtle differences between the rims. “The shape of the wheel rim has many design parameters. It has to allow the fitting of the tyre. It has to hold the tyre and allow an airtight seal to be created. It has to be light. It has to be as thin as possible to allow the biggest brakes to be fitted beneath it. It has to give good heat transfer and dispersion. It has to withstand tremendous forces without deforming. It has to enable good airflow to the brakes, but not create unwanted aerodynamic drag and its shape and width affect the spring rate of the tyre itself.”

As well as holding the tyre, there are other components which are mounted on a Formula One wheel rim. “Of course, there is the valve, which allows the tyre to be filled and deflated. Then there is the tyre pressure monitor. Sometimes there are other valves too, which allow the tyres to be purged.”

Every Aspect Of Rim Design Is Carefully Considered

Every element on the rim has to be carefully considered. Not only is the placement of the components important for their job, but they also need to allow the fitting and stripping of the tyres from the rims.

“Every aspect of rim design is carefully considered. For example, when the tyre is fitted our technicians manipulate the tyre over the rim, so valves and sensors have to be situated so they do not interfere with this, otherwise the fitting process becomes unnecessarily lengthy.”

Once the tyre is fitted to the rim, it is inflated with dried air. A combination of tyre and rim design ensures an air-tight seal.

“We use a fitting paste when we are fitting the tyres to the rims, but it is the deformation of the rubber at the tyre edge where it meets the rim that creates the air-tight seal and ensures that the tyre retains its pressure.”

Formula One Tyre And Wheel Rim Balancing

The tyre and rim combination then require balancing.

“Even a highly sophisticated Formula One tyre and rim requires balancing as there are subtle variations in the tyre and wheel as well as a valve and sensors connected to the wheel rim.

“An unbalanced wheel causes vibrations, making the job for the driver very unpleasant, and even potentially causing problems for components on the car. This means that ensuring that the wheel and tyre are balanced correctly is an important consideration for Bridgestone and the teams.

Balancing is an area where Bridgestone has recently made a change based on environmental considerations, with a change from lead weights to weights made from tin.

“Lead weights have been used in Formula One for many years as they offered a good technological solution as lead is a very dense metal so it is heavy for its size. We have worked closely with the teams and since the European Grand Prix this year we are using tin weights, which we also recycle afterwards.”

Every race weekend Bridgestone brings 1800 tyres to the circuit.

“We bring and fit a lot of tyres at a Grand Prix so it is important that everything works well with the tyres and the rims, and this is just another part of the interesting technology and logistics behind the races that many millions of fans see on televisions around the world.”