I live in LA and have a 4.8is and would suggest listening to the previous suggestions...I also drive up to Tahoe quite a bit and picked up a set of 18" snow wheels/tires this past summer...The 20's up in Tahoe are going to be completely useless, not to mention that if its snowing when you get up to Kaibers pass, they won't let you go through chains or no chains. Not only are these tires too wide, but when coupled with the 4.8's stump ripping power, I'd be surprised if you even made it a few inches in that heavy crud up in LT. Even with my brand new blizzaks, the 4.8 is constantly trying to stay hooked up. Also keep in mind that they have gotten 7+ feet of snow in the past couple weeks, you will most likely encounter a side road that still has 2 feet of snow on it unless you are driving straight into heavenly village and not leaving it.

Best car I ever drove in the snow(20years of snow driving) is still the old ass subaru station wagon 4x4 we had with 15" tires...that thing was absolutely unstoppable and had probably 90hp to the wheels! Haha

If you don't have any experience with the 20's in the snow, then it's probably best to avoid it. However, I have taken my car to mammoth a lot and a few times it was dumping snow. As others have said, it is VERY slick with the 20s but in mammoth if you don't go off on any steep hills and you keep your speed very slow, like 20 mph max, you will be able to get by. I didn't have too much trouble putzing around the town and to the ski lodge. Also, when you're rolling it will feel fine, but stopping is main issue. You just need to start slowing down well in advance, keep a lot of distance from the car in front of you and apply the brakes very lightly and gradually.

I don't have any experience with the roads in Tahoe.

Yep, you'll need at least 18's to fit over the front brakes on anything larger than 4.4...and not all BMW 18's will fit at that. I have the recommended winter setup from BMW on my 4.6is (purchased at huge expense by previous owner) and it transformed my X into a TANK in the snow :D

Getting up to Mammoth is a walk in the park compared with getting into Tahoe...If its snowing do not even attempt to drive through the pass with the Diamaris tires on, you will most likely end up off a cliff or in the side of a mountain...seriously.

If it isn't snowing you can probably drive in easy enough, but if you need to use any of the side roads you'll be up shits creek. Also keep in mind that the weather changes very quickly up there...Drove in last year with the roads completely clear and only flurries in the forcast for the overnight...woke up to 3+ feet of extremely heavy snow...Luckily, I had my Honda Ridgeline and had absolutely no problems...People were getting stuck all over the place.

Not that I'm looking to drop a bunch of $$$ on this little project...... Since not all wheels will fit, which one did you get? Any pics?

thanks
g

Not a very good pic, but you can get the idea. It is a style 99 in BMW-speak
http://farm4.static.flickr.com/3113/...76d9085526.jpg

Gbogh,
You already got the answer. I have a 4.4 and it can run the 17s. The 4.8 require the 18" because of the brakes sizing.
Good luck!

Thanks everyone for the great advice. I made it up to Tahoe without any problems, but there was less than 1 inch of snow on the ground. On surfaces that have been plowed and salted, traction wasn't bad. On surfaces that had some packed snow or ice, my X5 with Diamaris on 20s were sliding sideways while coming to a complete stop. Getting going isn't a problem, but like other posters have said, it's turning or stopping that's difficult.

This morning we woke up to about 6 inches of fresh snow. We're planning to head back to San Francisco this afternoon and there's just no way my X5 will make it. So we were lucky enough to find a gas station that would deliver and install chains for $140, not bad I guess. I foresee my 20" rims getting scratched all over, but oh well, at least I'll get home safe.

I'm definitely planning to get another set of tires or renting a 4x4 for my next Tahoe trip. This week all car rental places were completely sold out of 4x4 SUVs due to the holidays.

Merry Christmas everyone. Drive safe.

Well, turns out the garage guy who installed my chains did so improperly. The inside end of the chain became loose and severed my brake line. Now i have no power brakes and I'm stuck in South Lake Tahoe with my wife and kid. All garages, shops, etc are closed since it's Christmas and I can't get it towed to the nearest BMW shop until Mon/Tues. Looks like I'll have to find a car rental tomorrow to get home and leave the X5 with the towing guy until next week...

At least I have some sweet new chains on my X5! :(