Attention to Detail

If you talk to engineers at Goodyear Test Centre: Luxembourg (GTC*L), they will probably tell you just how radically “tyre testing has changed over the last 20 years” and how pleased they are to have been at the forefront of these developments. During a recent visit to the company’s Luxembourg operation, officials showed Tyres & Accessories just how far Goodyear is willing to go to develop and improve the comfort and safety of its products.

Nestled amongst the Goodyear Luxembourg complex which includes, tyre production, mould making an truck tyre mounting facilities, the GTC*L is made up of three main buildings; GTC*L itself the Tyre and Vehicle Testing Laboratory and Laboratory B. A day touring the Tyre and Vehicle testing laboratory alone is quite an education. In addition the people at the Goodyear’s neighbouring test track have a fleet of trucks, buses and cars that are perpetually testing tyres, clocking up 10 million kilometres a year. The quantity of data that the centre’s 44 PhDs wade through is immense, but here is just one example of the GTC*L’s daily activities.

Tuning tyres

Noise/vibration testing is one of those counter-intuitive areas where engineers work very hard, just so their efforts can literally go unnoticed. While most people would find this demoralising, going unnoticed is exactly what these guys strive for. The average consumer might not think they pay much focused attention to tyre noise while they cruise down the M1. But we’re a lot quicker to notice when this interrupts our driving experience or the dulcet tones of Radio 2.

As you might expect, the complete eradication of tyre noise is an impossible mission. The laws of physics dictate that whenever a revolving surface contacts another surface in air, sound waves will be produced. In addition to this, the fact that tyres routinely rotate at speeds of between 0 and 70 mph means the frequencies produced are likely to be within the human hearing range. As a result the process of noise reduction is really more about making sure drivers are unaware of any sounds, bringing a whole new meaning to the words ‘tuning tyres.’

Tyre engineers have been working along these lines for sometime. The now relatively commonplace use of different sized shoulder blocks is an example of this principle in action. By using different sized blocks and varying the spacing between them, recognisable noise levels can be kept to a minimum. But there is only so much that can be done to the tyre, and while Goodyear engineers make it clear that they are striving to solve these problems there are other aspects that must be considered.

In addition to the construction of the tyre itself, the way a product interacts with the vehicle it is attached to is also important. As we have already seen, the unavoidable sound/noise generated by the tyres can be minimised through design, but then there’s the rest of the car. Everything from rear-view mirrors to doors have the potential to vibrate and therefore can generate noise when the vehicle moves. The last thing tyre manufacturers want is for their latest luxury tyre’s low level hum to clash with the sound of a loose glove compartment.

“We avoid having multiple problems in the same frequency range,” one technician explained. One such key frequency range is between typical cruising speeds of 60 and 80 mph. However, as the saying goes, nothing in life is that simple. The problem is the exact frequency range of various ‘danger zones’ varies widely between different vehicles. Then there are the further differences between deluxe and standard models of the same car. Even the differences between prototype and production vehicles are considered.

Pre-production testing is said to be particularly challenging because although prototype vehicles are built to the same shape and dimensions as the finished product, they are often constructed in quite different ways. Prototypes are often hand welded rather than spot welded, making the vehicles slightly more rigid and therefore affecting the vibration of components like door and roof panels. In order to get round this problem, Goodyear representatives explain that they often test their products with some of the first mass production models that run off the construction line in order to ensure the tyres perform as expected.

So how does the R&D team assess all these little quirks? That’s where Goodyear’s vehicle test laboratory comes in. The attention to detail that the company puts into development is further emphasised by the amount of money it has invested in this process. Just one of the Luxembourg sound/comfort testing laboratories is made up of $2 million dollars worth of soundproofing and equipment.

Next door to the noise testing department, Goodyear runs another lab, which measures comfort – basically further experiments concerning vibrations, but looking at a different frequency range. Challenges in this area include the fact that most tyres oscillate on or around 70 hertz; and the inherent amplification properties of pneumatic tyres. So far, solid tyres are the only known way of getting rid of this ‘soundbox’ effect, Goodyear researchers explained.

The GTC*L also runs a tyre uniformity testing machine, which is capable of testing uniformity of tyres in conditions of up to 400 km/h. Once again, the company also conducts production line tests for uniformity. These measures ensure that any minor variations are kept within a specific tolerance level and frequency range.

Furthermore GTC*L staff also measure dynamic footprint criteria and treadwear. But these are just a few of the many more experiments that are carried out. And that’s why the Luxembourg site demonstrates the technology that goes into tyres and embodies powerful arguments against their commoditisation.