Buying tires is not an easy thing, but since 2012 consumers have been able to compare certain criteria with the help of the tire label. These criteria reflect certain characteristics of new tires. But how does a tire behave during its lifetime?? can a worn tire ever be safe enough? I learned more about the thematic and compare old against new.
"tires are tires!" you might think. But there’s a lot of know-how in rubber and tread. For such a tire to work well and safely in any conditions – and not only when it is new. But when is the time for a new tire?? And is it still safe to drive with a minimum profile??
Is a worn tire always bad?
With increasing use, various properties of a tire change. But a worn tire does not have to be bad. For example, the braking performance of a tire can improve because the contact area increases as the tread wears away. Another point is increasing efficiency. In worn condition, the coefficient of friction and thus the fuel consumption is reduced. The situation is often different in wet conditions. As the tread reduces, some tires also lose their good wet performance, which is important for safety!
practical test: differences in wet conditions
To illustrate the differences between new and used tires, michelin has prepared practical driving tests. on a watered roadway, several braking maneuvers from speed 80 should be completed. for the practical test several identical cars were equipped with different tires. Besides new tires with full tread (8 millimeters), the same tire model was also available in worn condition. In this case, worn meant that the tread was still 1.6 millimeters and therefore still met the minimum legal requirement.
Above a new tire with 8 mm profile. Below the same model in worn condition. This tire still has a minimum tread of 1.6 mm and can still be driven on.
In direct comparison, these 1.6 millimeters are shockingly little. In such a used condition one does not trust the tire much more. For this reason, most drivers do not hesitate and replace their tires much earlier.
Braking test on a wet road.
Braking distance
How important a minimum requirement or. The test with a foreign tire makes it clear that this would be a marker for used tires. Performed several brakings on wet roads. The distance from speed 80 to 20 km/h was measured. Where the new tire with full tread reaches a value between 49 and 55 meters, it is already over 70 meters in worn condition. A few meters can make all the difference, especially when braking at speed. Here the difference is already four (!) car lengths.
Traction on the handling crus
Even more impressive was the comparison on watered track. With the test vehicles audi A3 with front-wheel drive, you quickly got a good feeling about the tire’s performance on the circuit. I started my first comparison drive with the worn foreign tire. With normal speed I tried to feel my way to the adhesion limit. The tire gave me a bad feeling right from the start. No sooner had I got used to the conditions than the audi slid in a sharper outward-sloping corner and I promptly went off the track. Phew… although I also challenged this situation a bit but despite the feedback the tire gave me and the not particularly high speed, I was still surprised.
In the course of this comparison, under the same conditions and with identical vehicles, I could test the michelin pilot sport 4, which was designed to retain its consistency and to remain stable even when worn down or in the same condition. With a minimum tread of 1.6 millimeters, the tire still performs well in the wet. Despite its condition, the michelin tire felt positive throughout. On the one hand, the tire behaved consistently well over variously watered road surfaces without floating up, and on the other hand, it gave good feedback about the grip in curves.
Tread design for consistency over the entire service life
How exactly this tire manages this balancing act throughout its entire service life becomes clear when you look at the tread structure. the profile of the michelin tire resembles a "U" in this view. The width of the groove hardly changes with wear. A competitor’s model becomes progressively narrower due to its V-shaped grooves.
V-shaped tread blocks (left) of an avon tire. With increasing wear, the width of the longitudinal grooves is reduced. On the right, the U-shaped longitudinal profile of michelin. The width of the longitudinal grooves remains more constant with wear.
New production techniques: 3D printing in tire production
Why do such differences exist?? In addition to the tire compound, the driving characteristics are related to the tread design and also to tire production. The production of tires with V-shaped grooves is much easier. New technology in the production of tires now also allows new layouts in the creation of tire shapes. Previously, die-casting molds were used. Michelin molds now use molds that are produced using a 3D printing process and allow for significantly more complex designs. The U-shaped tread pattern described above can be achieved using the tire molds created in the sintering process. Depending on the tire model, even tread patterns that become wider towards the bottom (teardrop shape) are possible.
video recommendation: "michelin demands test for driven tires"
My colleague jens stratmann from voice-over-cars.Com went to michelin with me and produced a video about it:
Tire label for more transparency
Currently, the tire label offers some guidance. It looks similar to the labels found on refrigerators, televisions and other electrical appliances in electronics stores, providing information about their energy efficiency. A similar label is also available in the form of a tire label. Since 2012, tire manufacturers and retailers have been obliged to label the tires they offer. The tire label provides information about fuel efficiency, wet liability and rolling noise. The results of these criteria, established by an EU directive, are determined with new tires.
The tire label provides information on fuel efficiency, wet grip and rolling noise.
minimum requirements and more information for better comparability
what happens during the later use and how the tire behaves is not recognizable. From the customer’s point of view, safety during the entire service life is just as relevant as durability. Because length of use is not only a cost factor but also a sustainability factor. If a tire is replaced earlier than necessary, this has a negative impact on the environmental balance sheet.
Previous new tire tests also with used tires
The tire manufacturer michelin therefore supports the proposal to apply a minimum requirement for wet braking performance also for driven tires. Tire customers can better compare and use the tire longer and above all safer. A suitable requirement via a basic directive on vehicle safety is to be implemented before the end of fall 2019.
you like 3ve-blog.De?
Then tell others that you like our blog .