With the winter tyre market starting to develop in the UK, a lot of people have been discussing all season tyres. UK winters are characterised by long, cold wet spells, and when the snow falls our road systems grind to a halt due to 99% of the cars in use are running summer tyres.
For those people who don't want the hassle of changing their tyres twice a year, all season tyres seem like a logical compromise. Designed to work year round, in theory the all season tyre can offer 90% of the wet and dry performance of a summer tyre, combined with 90% of the performance of a winter tyre on the snow. If these tyres are able to offer that sort of performance, with similar year round qualities of a summer tyre, what are the draw backs?
The definition of a modern all season tyre is subject to a lot of debate in the tyre industry.
All tyres are a compromise of performances, and modern all season tyres, such as the Goodyear Vector 4Seasons, Vredestein Quatrac 3, Hankook Optimo 4S and Kleber Quadraxer could easily be defined as "wet optimised" winter tyres.
These modern all season tyres are patterned and siped like winter tyres, but use slightly less winter optimal compounds to improve wear and dry weather ability. Certain tyres from the Nordic companies are actually called winter tyres in the UK, but the same tyre is referenced as all season tyres in other climates.
To help us benchmark all season tyre performance, we've turned to the Auto Bild 2012 Winter tyre test. In that test, 15 winter tyres were tested, and they included a summer tyre, and the Goodyear Vector 4Seasons all season tyre.
For the purposes of consistency we will reference the Goodyear all season tyre, against the test winning Continental Winter Contact TS850, and the summer tyre.
It's no surprise the summer tyre doesn't perform on snow, nor is it a surprise that the all season tyre can't quite match the winter tyre in the same snowy conditions. What does get interesting is when we look at the wet, dry, wear and rolling resistance scores of each tyre.
Under dry braking the results are extremely close, with the winter and all season tyre stopping just 0.3 meters apart in favour of the all season. Change the surface to wet, and we find that the Continental winter tyre actually stops just 2 meters behind the summer tyre, while the all season tyre takes a further 5.2 meters to stop.
It's a similar picture during the handling tests. The summer tyre couldn't even manage a lap on snow, while the all season tyre got within 3.5 kph of the winter. In both the wet and dry the summer leads by a margin, but in both these tests it's the winter that out performs the all season tyre. Not what we'd necessarily expect.
The Goodyear has a slightly higher projected mileage, at 38550 kms compared to 33700 for the winter (the summer tyre wasn't tested), and during the rolling resistance tests it was actually the Continental winter tyre which had the lowest rolling resistance, so would use the least fuel.
What can we conclude from this test? The evidence suggests that the technology to create a true all season tyre doesn't yet exist, and looking at the balance of qualities, the best winter tyre on sale in the UK is actually a better year round tyre than the leading all season contender. The Continental works better in the snow, better in the wet during handling, braking and aquaplaning tests, and in the dry it's only narrowly beaten under dry braking, but wins again during the dry handling tests. We’re waiting for the confirmation of the wet and dry test temperatures, but we believe them to be around 7c.
All tyres are a compromise, and a siped tyre with a compound designed to work in a large range of conditions is more of a compromise than most. Unfortunately, a true all season tyre still doesn't exist, and for optimum year round grip we need to run two sets of tyres. As a summer tyre offers little to no performance in the snow, an all season, or good quality winter tyre can be a sensible year round compromise if you don't want the bother of running two sets of wheels, but want to be mobile regardless of the conditions.
The Continental Winter Contact TS850 has moved the game on for winter tyres, and based on these test results, would anyone question if it was labelled an all season tyre?