Right now, I'm going to say the OEM 20" Goodyear RS-A tires are basically worthless in all types of snow - deep snow, packed snow, ice, slush. There is basically zero traction. I was testing the rig out a bit before packing up for the drive to Vermont for the weekend and had to postpone the trip as we had 6" on the ground and 12"+ was predicted in VT - yes, it was going to snow the entire trip. I traded our Yukon XL for the Flex, and never once have questioned the 4WD prowess of that truck.
On to the test, on a slight incline (5% to 10% grade, no more) in our driveway, I tested both my 2010 535xi and my 2010 Flex AWD - the BMW on Continental DWS and the Flex on the RS-As. The BMW went up the hill from a stop with no drama, no issues whatsoever. The Flex wouldn't budge. Traction on, traction off, no difference, just more aggressive wheel spin. This crappy Haldex AWD is very similar to what we had in a Volvo XC70 Cross Country some time ago - basically front wheel drive with a bit of torque to the rear wheels. Moving shifter into drive with no throttle just started the front wheels spinning. I should have taken a video, as I'd be skeptical reading this.
So last night, I placed an order to Tirerack last night for a set of snow tires for our Flex. We'll see if the Pirelli Scorpians make a difference - if they don't, I'll be forced to sell it to trade back the dreaded yestertech of the Yukon XL (we test drove one Saturday, and the technology package is ancient when compared to Sync and NAV in the flex)
Will keep you posted.
Edited by Gundo, 10 January 2011 - 06:35 AM.