Why do racing cars have wide tires?

Tire size: better narrow or wide?

Would you rather be discreetly narrow or rather noticeably wide? An evaluation of the ADAC tire tests explains the advantages and disadvantages of thin or wide tires.

Surface Wide tires see just cooler out! At least that's what the many vehicle owners think, who opt for wide tires with large rims so that their car looks more stylish and better proportioned. Such a beauty cure is worth an extra 2,000 euros for them.

But do wide tires also offer technical advantages? The ADAC has evaluated its summer tire tests of recent years for this question. On inspection four were very much different tire sizes in 15, 16, 17 and 18 inchesall for the VW Golf VII allowed are. A was used as an additional reference Dimension comparison with a winter tire of the same profile and rubber compound.

Wide tires stick better

The result: up dry road surface meets the formula "The wider, the more grip" unreservedly to. Due to the lower flank height, the tire becomes stiffer and handling is noticeably improved. With increasing width, i.e. more rubber on the road, and a stiffer structure of the carcass brake wider tires on dry roads too faster and better.

The Braking distance from 100 km / h decreases significantly: the small 195-inch tires come to a standstill after an average of 38.8 meters in the ADAC tire test, almost two meters later than the 225 mm wide and flatter 18-inch tires (36.7 m).

Dangerous aquaplaning

On too Wetness the wider tires dominate - as long as the micro-toothing of the tire rubber engages with the road. Since with every centimeter more width but also more water has to be displaced, swim the Wide tires with dangerous aquaplaningearlier on.

The graphic shows the speed at which a water wedge pushes itself under the tire contact area and thus to the Loss of Liability comes. With the narrow tires you can drive over ten km / h faster on a straight stretch before the car floats up.

Which tire fits?

How can it be that four such different tire sizes are allowed on the VW Golf? That works because all tires have the same rolling circumference to have. If this were not the case, the Golf's electronic auxiliary systems, such as ABS and ESP, or the speedometer could no longer function correctly.

The rolling circumference is defined by the ratio of the rim size, the height of the side flank and the tire width. The tire designation provides information on the key figures for these factors. Example 225/40 R18 Y: 225 is the Tire width in mm, 40 gives the Tire or sidewall height in relation to the width in percent, R stands for the Radial tire design, 18 for the Rim diameter in inches and Y marks the Speed ‚Äč‚Äčindex (allowed up to 300 km / h).

Which tire sizes are approved for the vehicle can be seen from the information in lines 15.1 and 15.2 of the "Registration Certificate Part 1". Only one size is entered here. The so-called CoC document, which every buyer receives when purchasing a vehicle, contains other approved tire dimensions.

Narrow springs better

Because the Flank height the wide tire is smaller (the rolling circumference must not change), there is less air available for suspension and the Side wall is stiffer. The effect: wide models drive noticeably on the Golf more uncomfortable than thin.

The graphic shows the measurement results of the ADAC tire test, which evaluates the data from sensors installed under the driver's seat: Narrow tires (195 mm) thanks to their higher side wall significantly more suspension potential than the wide and flatter tires with the low cross-sections.

Broad: Less wear and tear, more consumption

The more stable side wall has a positive effect on the wear from the wider tires has to do less flexing work than the narrower one with better distributed ground contact, so lasts longer.

But especially economically wider tires are still not. Because for higher purchase price he comes Additional consumption: 18-inchers weigh around five kilos more per wheel than 15-inchers - and the weight has to be accelerated again and again every time you start off. In addition, there is a higher rolling resistance, because the air resistance also increases when driving - with a width increase of 30 millimeters by around six percent.

Winter tires: same principle

In principle, the same applies to winter tires as to summer tires. But on snow and slush drives the narrowest dimension 195/65 R15 a good deal safer than the broader colleagues: Above all, starting off, but also cornering are better. The risk of aquaplaning in slush is also lower.

Anyone who opts for wide tires should also check whether they can still be used to mount snow chains on the car. Because wider rims are often not suitable for this. And you should recalculate: Narrow tires are cheaper. In the case treated here, between narrow and extra wide are around 85 euros - each!

You can find even more information in the ADAC guide:The most important tips for buying tires

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