Winter driving
 

I'm planning on going to the US this December with my family and going on a road trip to Yosemite and/or Lake Tahoe. Am I required to put on tire chains on an AWD SUV like X5? It's got traction control as well.

If you plan to drive extensively in snowy areas, I suggest you find a set of winter tires and even snow chains. The former is always a good idea because summer and all-seasons won't cut it at those elevations, and the latter may be required, although maybe the Californians can chime in whether they allow un-chained winter tyres.

Here are some useful URLS. You'd want the same for Nevada as well as you can easily go back and forth between the two states up in the sierras. I personally have not seen 4X4s putting on chain. They tend to be let through at controls but you might want to purchase a set and bring it so you can prove that you can use it if necessary. Check your X5 manual too.

California Road Conditions:
Road Conditions

Webcams of key areas -- very handy!
Caltrans :: Live Traffic Cameras

The stated regulation from the above page:
Chain Requirements:

• R1: Chains, traction devices or snow tires are required on the drive axle of all vehicles except four wheel/ all wheel drive vehicles.
• R2: Chains or traction devices are required on all vehicles except four wheel/ all wheel drive vehicles with snow-tread tires on all four wheels.
  (NOTE: Four wheel/all wheel drive vehicles must carry traction devices in chain control areas.)
• R3: Chains or traction devices are required on all vehicles, no exceptions.

Your going to need snow tires if you want good grip on snow. X5 handles nicely on snow roads with winter tires, don't know about deep snow though... Remember its not really an AWD car. Snow and Slum Mud can push the limit of traction on normal tyres on an X5, no matter how sophisticated DTC is.

The area in California and Nevada that the OP is asking about has specific laws concerning the use of snow tires and chains, he's not asking about whether he needs them for regular winter driving, he's asking what the laws are in the area.

Thanks guys. So the conclusion is I might be required to put on chains depending on the condition. I wonder if the rental car company has an optional winter tires.

Yes, it's XDRIVE and it's better than pure AWD :)

What exactly is x-drive?? A set of "studless" snow tires is highly recommended. They are the Shite! I have run them for years and regularly drive in snow all winter long out west!

Remember that AWD or 4WD only helps you accelerate. It does not help you stop or turn (when the gas pedal is released) It would be a good idea to have snow tires, chains or both. These things are a lot cheaper than a trip to the body shop.