MDX is my first SUV and am planning a trip to Tahoe for skiing soon. So when CalTrans says snow tires/chains required on I-50/I-80, what does that mean to me? Do I need to get chain or have snow tires installed in my MDX? If not, should I press the VTM-Lock button to drive in that situation?
Cal trans has several stages of highway control for going over I-80 & 50. R1 means Ok to travel if your 2wd car has M&S rated tires. R2 means Chains only for 2wd but 4wd, (the MDX), Ok if equipped with M&S rated tires--it is. R3 is 4wd with chains/cables only--at that point Cal Trans usually just closes the highway.
The MDX has 2 types of standard tires, both are rated M&S, (Mud & Snow). My experience with the last 4 feet of snow we just got here is that the Michelin Cross-terrains did very well in the snow, not so good gripping in an icey turn, --(just go slowly when you turn). All 4wd are supposed to carry chains/cables but in the 30 years driving in Tahoe I have NEVER been asked or checked. Acura says you can not use chains on the MDX but lots of poster have found cable chains that fit.
You do not need to push the VTM lock the MDX automatically switches into 4wd as needed. VTM lock won't work above 18mph anyway. Read your book re: VTM lock.
By law in CA you are required to carry chains in the mountains when snow is likely. Of course 90% of SUV owners do not even own chains! I have never been asked to prove that I am carrying chains.
It is very rare on the major highways that chains are required on 4WD and the road is still open. However, there are places like the road to Badger Pass in Yosemite where they frequently require chains at the end of the day to drive down - I have known people to be trapped in the park because they are not allowed to drive down the hill!
VTM-4 is only available in 1st and 2nd gears and only then if you are stuck and need to lock the differential. It could do damage if used incorrectly.
For that reason you mentioned, I ordered cables for my X to take on a trip to Snow Summit up in Big Bear next week. Though I probably won't need them, it would be wise for me to have them.
There is a thread about snow chains, actually cables describing the two types of cables. ZT729 and ZL671. The latter cost a little more but the cheaper of the two uses rubber fasterners which are not advised for the shape of the wheel... Anyway, if you live in the South Bay area, I believe someone posted that Winchester Auto Parts ($78 and $107) has the best price, otherwise online, Howards has them shipped for under $100 and $135 (respectively). Also, within the thread, a couple people make a good argument as to why it would be better to put the cables on the rear vs. the front.