@ Hightech,
I have purchased the WRG2s for my RAV4 after extensive research of a "one tire for everything" solution, and while I have not driven them in deep snow or ice yet, I can say they have been very good thus far, with regard to tread life, noise, tire feel, etc. I used Consumer Reports when I was looking for this type of tire, and their reviews last year led me to the WRG2.
I also was confused when I saw that the Primary MXV4 outscored the Nokian on Ice traction, but one thought did occur to me.
The Primacy does not have the Severe service emblem, whereas the Nokian does. This means that the Nokian does use a softer rubber compound, and a tread pattern optimized for use on snow and ice (hence the worse rating for tread life, it will wear out quicker as it has softer rubber). If you look into how Consumer Reports tests the ice traction of tires, you'll see that they do acceleration and braking tests on a indoor skating rink (see the picture associated with the article). This is NOT a good area to test braking performance.
The reason is because inside a skating rink, the ambient temperature is around 7-10 degrees celcius. It isn't until below at least 7 degrees celcius that All season tires begin to loose rubber elasticity, and become hard. So if the test were to be done on a skating rink OUTDOORS, where the ambient temperature was well below freezing, I think they would find that the WRG2 stayed much more pliable, and stopped quicker, as winter tires are supposed to, whereas the MXV4 would become much firmer, and loose it's ability to stop quickly on ice.
Just a thought. I have no evidence to back this up, but it seems logical. All seasons become hard below 7 degrees celcius. Indoor testing would not bring the rubber temperature below this level, even though the tires are sitting on ice. The Ambient temperature inside a skating rink will allow even the all seasons to stay soft and supple.
This begs the question, how come the MXV4 is able to stop better on ice than a winter tire at these warmer temperatures? Well, I have a theory about that as well, again just a THEORY. At temperatures above 7 celcius, and certainly around the indoor temperature of the arena, the tires are not relying on winter technology to stop( ie; siping, rubber compounds), because these are not winter-like temperatures. This is where the tread design might play a role. The MXV4 seems to have a much less aggressive tread design, with less open, "chunky spaces" than the WRG2. So it would make sense that on pavement, and even on ice where ambient temperatures allowed the tires to stay above 7 celcius, that the MXV4 would be able to stop quicker, as it would have more actual rubber in contact with the ground surface at any given time. More tire surface in contact with the ground means more braking forces (traction) is able to be applied to through the tires and to the ground, meaning a quicker stop. This is one of the reasons it is recommeded to NOT run winter tires in summer, as they do not handle/stop as well in warmer temperatures.
Again, this is all speculation, but logic would seem to dictate these ideas will hold water. The bottom line is this: PERFECT is the enemy of GOOD. A blizzak WS60 or X-ice Xi2 may be PERFECT on ice and snow, however the MAJORITY of the time in winter, the roads are cleared, but quite cold (-20 celcius, etc). On cleared road conditions, and in the wet, slushy muck which often happens on the "shoulder" season of winter tire use, these PERFECT tires on ice and snow become quite UN-PERFECT on other road surfaces. The WRG2 sounds like it will be a GOOD perfomer in the MAJORITY of weather conditions, which means that in reality, it could potentially be safer than a dedicated winter tire that becomes sloppy on dry and wet handling. The same goes for studded tires that are PERFECT on ice, but decrease traction and cornering ability on snow and dry/wet roads.
I'm a Paramedic, and we use studded Nokian tires on our ambulances, from mid october to mid april, and I can tell you it is SCARY cornering at high speeds when there is NOT ice on the ground. They slide out often, and don't grab nearly as well as even an all season would.
Keep in mind as well, that while there is a difference between a quality and a cheap winter tire, there is a much bigger difference between running an all-season tire (one not bearing the severe service emblem) and running a winter tire, such as the WRG2.
Hope this helps. Good luck.
