Information is from VTI (Swedish National Road and Transport Research Institute):
https://www.vti.se/en/news/winter-tyres-small-differences-in-grip-on-wet-asphalt/
Quote
Researchers at the Swedish Road and Transport Research Institute (VTI) have studied how grip on wet asphalt under winter conditions deteriorates with the age and wear of different types of winter tyres.
"We focused in particular on comparing studded and non-studded winter tyres in the testing.
We found that the braking and steering performance of studded tyres and Nordic-type tyres on snow-free ground is practically the same for both new and used tyres", said VTI researcher Mattias Hjort.
The winter tyres were divided into three main categories: studded tyres, non-studded tyres of Nordic type, and non-studded winter tyres of Central European type. A smaller group of summer tyres was tested for the purpose of comparison, and both premium and budget tyres were included in the tests.
"When it comes to new tyres, the Central European-type tyres perform roughly 10-13% better than do the other two types of winter tyres. This pertains to both braking and steering", said Hjort.
In the case of the studded and Nordic-type tyres, there was practically no difference in braking performance between new and worn tyres.
Both the Nordic and Central European types of winter tyres clearly exhibited a greater range of braking performance than did the studded tyres, this being true of both new and worn tyres. In contrast, the steering performance did not differ between the tyre types.
The final report (mostly in Swedish): http://vti.diva-portal.org/smash/get/diva2:956515/FULLTEXT01.pdf
Quote
This study has measured road grip on wet, salted asphalt road at freezing temperatures for used and new winter tyres, with the purpose to investigate how the road grip for the three different types of winter tyres that exist in Sweden degrade by age and degree of wear. Also summer tyres were included in the study.
In total, 84 tyres have been tested, of which 31 were completely new while 53 were used. The tyres have been tested on wet, salted asphalt road at temperatures around zero degrees Celsius. All tyres were tested using VTI's mobile tyre test equipment, the BV12. These tests measured the braking and steering performance of the tyres. A subgroup of tyres (50, of which 16 were new and 34 used) were also tested with a passenger car, which measured braking performance.
The winter tyres are divided into three main types: studded winter tyres, unstudded winter tyres made for Nordic conditions, and unstudded winter tyres made for central European conditions. In this report referred to as studded, Nordic and European tyres. In addition, a smaller group of summer tyres were also tested for comparison. Both premium and budget tyres were tested. The used tyres for selected after a survey of the condition of used winter tyres at four different tyre hotels, two of which situated close to Stockholm. All the used tyres had a tread depth between 5 and 7 millimetres, and the average age for the winter tyres of each selected subgroup were 5.5 years. The share of tyres from different manufacturers was chosen so that if possible it would agree with the market share found in the survey. The condition of the studded tyres was chosen in order to be representative for the condition of the studded tyres stored at the tyre hotels. This means that studded tyres both in good and bad condition were selected. In some cases, the set of tyres tested on a car were illegal, since the number of studs differed too much between the four tyres.
ï‚· Studded tyres and unstudded Nordic winter tyres have the same performance, for both braking and steering. This applies to new as well as used tyres.
ï‚· For new tyres, the European winter tyres performs 10-13 per cent better than the two other types of winter tyres. This applies to both braking and steering.
ï‚· For studded tyres and Nordic winter tyres there is no difference in brake performance between new and worn tyres.
ï‚· The worn European winter tyres have worse brake performance than the new ones. The worn European tyres have 5 per cent better brake performance than the worn studded and Nordic winter tyres.
ï‚· A comparison of the steer performance between new and worn tyres were made and no difference could be seen for either studded tyres or Nordic winter tyres with respect to maximum lateral friction force. The worn European winter tyres have somewhat lower maximum lateral friction force compared to new ones. Still, they are better than the worn studded and Nordic winter tyres.
ï‚· For all categories of tyres, the steer performance at high slip angles is 5-8 Per cent lower for worn tyres compared to new.
ï‚· The unstudded winter tyres show a larger variation of brake performance within each group compared to the studded tyres. This was seen for both new and worn tyres. For steer performance no difference in variation was found for the different types of tyres.
ï‚· The summer tyres perform as good as, or better than the European winter tyres. This applies to both new and worn tyres.
It must be stressed that it is not suitable to use summer tyres at these low temperatures since they are much worse than winter tyres in icy conditions. Other studies have shown that for a winter tyre, ice and snow grip are the most important properties with respect to accident risk. The previous VTI study showed that the European tyres perform much worse than studded tyres or Nordic winter tyres on ice and snow.
https://www.vti.se/en/news/winter-tyres-small-differences-in-grip-on-wet-asphalt/
Quote
Researchers at the Swedish Road and Transport Research Institute (VTI) have studied how grip on wet asphalt under winter conditions deteriorates with the age and wear of different types of winter tyres.
"We focused in particular on comparing studded and non-studded winter tyres in the testing.
We found that the braking and steering performance of studded tyres and Nordic-type tyres on snow-free ground is practically the same for both new and used tyres", said VTI researcher Mattias Hjort.
The winter tyres were divided into three main categories: studded tyres, non-studded tyres of Nordic type, and non-studded winter tyres of Central European type. A smaller group of summer tyres was tested for the purpose of comparison, and both premium and budget tyres were included in the tests.
"When it comes to new tyres, the Central European-type tyres perform roughly 10-13% better than do the other two types of winter tyres. This pertains to both braking and steering", said Hjort.
In the case of the studded and Nordic-type tyres, there was practically no difference in braking performance between new and worn tyres.
Both the Nordic and Central European types of winter tyres clearly exhibited a greater range of braking performance than did the studded tyres, this being true of both new and worn tyres. In contrast, the steering performance did not differ between the tyre types.
The final report (mostly in Swedish): http://vti.diva-portal.org/smash/get/diva2:956515/FULLTEXT01.pdf
Quote
This study has measured road grip on wet, salted asphalt road at freezing temperatures for used and new winter tyres, with the purpose to investigate how the road grip for the three different types of winter tyres that exist in Sweden degrade by age and degree of wear. Also summer tyres were included in the study.
In total, 84 tyres have been tested, of which 31 were completely new while 53 were used. The tyres have been tested on wet, salted asphalt road at temperatures around zero degrees Celsius. All tyres were tested using VTI's mobile tyre test equipment, the BV12. These tests measured the braking and steering performance of the tyres. A subgroup of tyres (50, of which 16 were new and 34 used) were also tested with a passenger car, which measured braking performance.
The winter tyres are divided into three main types: studded winter tyres, unstudded winter tyres made for Nordic conditions, and unstudded winter tyres made for central European conditions. In this report referred to as studded, Nordic and European tyres. In addition, a smaller group of summer tyres were also tested for comparison. Both premium and budget tyres were tested. The used tyres for selected after a survey of the condition of used winter tyres at four different tyre hotels, two of which situated close to Stockholm. All the used tyres had a tread depth between 5 and 7 millimetres, and the average age for the winter tyres of each selected subgroup were 5.5 years. The share of tyres from different manufacturers was chosen so that if possible it would agree with the market share found in the survey. The condition of the studded tyres was chosen in order to be representative for the condition of the studded tyres stored at the tyre hotels. This means that studded tyres both in good and bad condition were selected. In some cases, the set of tyres tested on a car were illegal, since the number of studs differed too much between the four tyres.
ï‚· Studded tyres and unstudded Nordic winter tyres have the same performance, for both braking and steering. This applies to new as well as used tyres.
ï‚· For new tyres, the European winter tyres performs 10-13 per cent better than the two other types of winter tyres. This applies to both braking and steering.
ï‚· For studded tyres and Nordic winter tyres there is no difference in brake performance between new and worn tyres.
ï‚· The worn European winter tyres have worse brake performance than the new ones. The worn European tyres have 5 per cent better brake performance than the worn studded and Nordic winter tyres.
ï‚· A comparison of the steer performance between new and worn tyres were made and no difference could be seen for either studded tyres or Nordic winter tyres with respect to maximum lateral friction force. The worn European winter tyres have somewhat lower maximum lateral friction force compared to new ones. Still, they are better than the worn studded and Nordic winter tyres.
ï‚· For all categories of tyres, the steer performance at high slip angles is 5-8 Per cent lower for worn tyres compared to new.
ï‚· The unstudded winter tyres show a larger variation of brake performance within each group compared to the studded tyres. This was seen for both new and worn tyres. For steer performance no difference in variation was found for the different types of tyres.
ï‚· The summer tyres perform as good as, or better than the European winter tyres. This applies to both new and worn tyres.
It must be stressed that it is not suitable to use summer tyres at these low temperatures since they are much worse than winter tyres in icy conditions. Other studies have shown that for a winter tyre, ice and snow grip are the most important properties with respect to accident risk. The previous VTI study showed that the European tyres perform much worse than studded tyres or Nordic winter tyres on ice and snow.
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