New winter tires are better than all-season tires in winter conditions; of course you knew that already. But how do these tires measure up when they’ve been used a season or two, or even more?
Last year, Canadian retailer Kal Tire commissioned a series of independently conducted tests that measured cold weather performance of new winter tires against that of new all-season tires. The results conclusively proved that winter tires outperform all-season tires on ice, wet and even dry conditions when temperatures were below 7 degrees Celsius.
This year, Kal Tire set out to replicate those tests, but this time using worn tires. The goal being to find out how various tires performed when they were no longer factory fresh.
The big surprise
According to the test results, a premium winter tire that’s even 75% worn out, can brake and corner better than a brand-new all-season tire in snow and on ice.
The testing program included what Kal Tire identifies as premium winter tires and economy winter tires. And while both premium and economy offerings behaved similarly when new, the performance of economy winter tires worsened as the tires reached greater states of wear. And while any winter tire, even one that’s been worn in, seems a better option than all-season tires, premium winter tires will see better performance retention as the tires cover more distance and time.
Worn vs new
Here are a few numbers to help put things in perspective.
If you hit the brakes on an icy surface while doing just 30 km/h, it would take a 75% worn premium winter tire 29.7 metres to come to a stop. A brand new all-season tire would need 32.3 metres, or 2.6 metres more – almost half a car-length.
The same test done with the 75% worn economy winter tire saw the vehicle come to a stop at 32.5 metres. That’s 0.2 metres worse than a brand new all-season tire, and 2.8 metres worse than a similarly worn premium winter tire.
For the sake of comparison, a 75% worn all-season tire took 35.9 m to stop – about a full car-length more than a 75% worn premium winter tire.
With fresh tread, premium winter tires stop in just 25.7 m, economy winter tires in 25.9 m, and all-seasons in 32.3 m as mentioned earlier.
When cornering in the snow at just 50 km/h, premium winter tires that are 75% worn hold a corner 4.3% better than a brand new all-season tire. Similarly worn all-season tires are said to be completely unable to hold the same corner.
While the testing covered tire wear points ranging from new, 25% worn, 50% worn, 75% worn, and completely worn, Transport Canada recommends that tires being used on snow-covered roads should be replaced before reaching 75% wear (5/32” or 4 millimetres tread depth to be exact).
Test procedures explained
This worn tire testing program focused on two primary scenarios: snow cornering at 50 km/h and ice braking at 30 km/h. The tests for both situations across all the tires were carried out in an outdoor test environment in British Columbia.
The testing used the Nokian Hakkapeliitta R2 as the premium tire, the Goodride SW608 as the economy tire, and the Nokian Entyre 2.0 as the all-season tire. Kal Tire identifies these as popular options with their customers and the reason for using them in testing.
Each tire was tested as new, at full tread depth (12/32”), at 25 percent wear (9.5/32”), at 50 percent wear (7/32”), at 75 percent wear (4.5/32”), and finally at full wear (2/32”) at which point a tire is considered bald.
For the purposes of testing, the tires were mechanically worn down to the tested tread depths in order to eliminate variables. It is worth noting that in real world applications, tires at these various stages of wear would also be subject to the degradation of rubber due to time.
The testing was carried out by an independent test group led by veteran racing driver, tire and vehicle tester, and driving instructor Alan Sidorov. Contracted by KalTire, Sidorov and his team work independently from their client to carry out tests of the tires selected by the client.
In an earlier interview with Autofile, Sidorov explained how he and the team take into account air temperature, ground temperature, wind speed, and brake pad wear on the test vehicles, along with suspension set up and even whether or not the sun was hitting the ice during ice tests.
While individual user experiences may vary, the data collected from the testing can be summarized as follows:
> Winter tires, even when worn, perform better than new all-season tires when temperatures drop below 7 degrees Celsius.
> Once beyond 50% wear, a premium winter tire will perform significantly better than an economy winter tire.