I have 18" Blizzak's. I had been driving on my all seasons and then we got bombed with 8" in one day and my X sucked on the snow. Threw on the snows and what a difference. Great traction and braking. I drive a twisty road to the skill hill for 45 mins and never feel like I have an issue with the snow and ice when I have my snow tires on.

I did own a 2004 Passat 1.8T 4Motion and that car was QUITE good in the snow even with the all seasons.

I'm on Hakkapeliitta's and the X5 handles Xtremely well in the snow and ice. I'm not familiar with the Dunlops but that could be part of the issue.

Braking on ice and snow is all about the tires and vehicle weight. Theoretically, an X5 braking on snow/ice would be like any other vehicle of the same weight on the same tires.

But what would I know, I haven't even driven mine in the snow yet. Just put on the new winter shoes yesterday - Pirelli Ice & Snow on 17s. My sister had these on her Range Rover and said they worked great in the snow, plus it sounds like a lot of people on this forum had positive experiences with the tire.

I'm pretty excited to test the X in snow (just purchased 2 months ago) and find the limits of what it can do. I've driven a few different vehicles in snow:
Lifted Dodge Ram 4X4 on off-road style M+S rated tires
Jeep Cherokee 4X4 on M+S tires
Volvo XC90 (AWD) on all-season tires
Toyota Celica (FWD) on street tires, with and without chains
Yes, I drove a Celica in the snow on low-profile street tires without chains. It was an emergency situation and I do not recommend anybody do this!

I'll see shortly how my X5 measures up and report back.

I have the same Dunlops on 18s. They ran very good when new, but after 3 seasons and 25k miles on them, they are starting to slip. I had no problems the first two seasons through any snow or ice.

I have a dedicated winter set in the recommended 255/55-18 size, of Bridgestone Blizzak LM-25 4x4s. I was able to get around with no problem even when over 2 feet of snow dropped on Ithaca continuously for 5 days in February/March.

The only bad experience I've had in snow was when I was driving on 1/2" of snow with the stock 20" wide ass summer tires when I first got the X5, before my winter set had arrived. I was responding to a car accident as a FF/EMT, and I thought for a split second I was going to become part of the accident when I was pulling up on scene...

I definitely looked like this: :yikes: :whew:

I made the mistake of taking the M5 out in the snow and taking it to work one day...I was all over the place. Even worse was the guy in front of me in a Corvette. The problem w/ sports cars, maybe even the X5, is that the width of the tires is actually worse to have in snow vs skinny tires. Having wide tires IS just like having snow shoes on...you stay on top, but that's not beneficial for a car that needs traction to go forward vs being able to lift your foot straight up and forward for movement.

Once the snow starts hitting here in Boise, ID, the cars stay parked in the garage and I spend more time driving my 90 S10 Blazer w/ skinny little 195 tires that drives AWESOME in the snow. I've driven the X in the snow to Reno, but it is a little sketchy, and while the electronics are there to save me, they can also be a little intrusive as well.

Wide tires w/ small sidewalls are great on dry pavement, but skinny and tall sidewalled tires are the key to being able to drive around in deep snow...look at images of rally cars in the snow as they have the skinniest damn tires w/ big sidewalls.

:iagree: That's why it's impossible to find winter tires that fit the rears on the stock 4.8is setup. It's simple physics: pressure=force/area. With wide tires, you're splitting up the same weight of the car on more surface area, which is not what you want in the snow. For greater traction, you want the same weight on less surface area, so you want skinny tires. However, I'm assuming BMW recommends the 255/55s because it's a good balance between being decently skinny, compared to the stock tires, yet wide enough so that you don't lose that much performance during dry conditions, especially because winter tires have softer rubber than all-season or summer compounds.

There are a couple of physics problems with this. The first is that pressure on the inside and outside of the tire are the same (putting aside sidewall stiffness issues). So, if your tires have 32 psi, then that is your ground pressure. It doesn't matter how wide the tire is.

Larger tires simply don't have more rubber on the ground, that is a common misperception. A wide tire and a narrow tire have exactly the same footprint in area. They just have a different shaped footprint, either short and wide or long and narrow.

A wider tire doesn't float because it has more area. It can hydroplane easier because it is harder to squeeze the water out the side. A wider tire does have to 'climb up' the leading edge in snow, and it has a wider leading edge. A narrower tire cuts through better, and the rest of the footprint follows in the track created by the narrower leading edge.

Amen. Pirellis are like glue. 19's and i have to really try to slide around.

You didn't pick the wrong tire ...I have driven the Dunlops (17's) in the worst winter conditions in MA/ME/NH/VT and they have been awesome. Might be just different to what you were used to - my X does not handle in the deep snow as good as my old jeep either.

No need for any hand wringing for anyone buying winter tires. Any of the top rated winter tires will be equiv - Dunlop grandtrek, Pirelli Scorp., Hakkas, Blizzak etc. etc. - we are not entering the scandinavian ice rallying circuit ;)