Here is a very recent (Nov 2009) tire comparison that Car and Driver did:
http://www.caranddriver.com/feat ... es-comparison_tests
C&D's comparison was between 4 Michelin tires:
1) high performance all season
2) all season touring
3) winter performance
4) dedicated winter tire
If you are too lazy to read the entire article, you can skip straight to the hard performance data at the end of each tire review. But don't take the data values too literally just yet, because as purely objective data, they don't take subjective considerations of everyday life into account.
At first glance, the high performance all season and all season touring fell flat on its face the moment there is snow. The dedicated winter tire did almost 20% better than the performance all season in snowy conditions. This was to be expected, and there were no surprises here. And 20% is a significant amount.
On the other hand, it seems like both all season tires did better than the winter tires in the dry and in the wet. So jh66 might very well claim this as rock solid proof that all season tires are more appropriate for Vancouver's weather since we don't get all that much snow. While the hard data doesn't lie, and the dry and wet performance of the all season tires are truly superior to those of the winter tires, we really need to take reality into account as part of our consideration -- that is to say, 1) how much of the performance do we really tap into when we drive on the street, and 2) what conditions do we find ourselves in when we drive?
I ran some tests with my (vehicle) data logger back in October when I still had summer tires mounted on my car. For street driving, my turns generally do not pull any more than 0.3g's worth of lateral acceleration (and really, the norm more or less hovers around a boring 0.2g). Accel- and deceleration can be up to almost 0.4g, but usually they don't exceed the 0.3g mark either. What that means is, in 99% of the time, I never ask my tires to do anything more than 0.4g's worth of work on the streets, and any additional performance beyond that means absolutely nothing since they'll never be tapped into (unless I decide to drive recklessly, of course). Keep this thought in mind when we examine Vancouver's winter road conditions.
Now for the really important bit -- under what conditions are we most prone to accidents in Vancouver's winter? Answer: frosty mornings/evenings and black ice. What this means is, in the moments when you are most likely to get into accidents, your car is driving on morning / evening frost and/or black ice, and you are asking the car to pull 0.3g's worth of acceleration longitudinally or laterally. That means the dry or wet tire performance of 0.8-something g means absolutely nothing, because your all season tire can only muster up 0.24 to 0.28g's worth of acceleration. Since your tires can't offer enough grip, your cars plows or slides, and you get into an accident.
Now, with my Michelin X-Ice 2, the tire can pull a maximum of 0.33g, and the turn only requires 0.3g. Tada~ I have enough grip in my tires, and I drive on happily without getting into an accident.
Honestly, I didn't make up any of the numbers at all. But everything just fall into place, and everything makes perfect sense.
So while all season tires are adequate, why won't you invest into a set of winter tires? It could mean the difference between getting stuck or moving on in some cases, and it could mean the difference between crashing and narrowly avoiding an accident.
-Lik |
發表於 2009-12-6 11:56
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lol