Snow Tyres vs mud/off-road tyres:
2 seasons ago, I was giving my aunt & uncle a lift to Chambery airport after they'd been skiing with us. It was late January, so usually the traffic on the roads on changeover day is OK (can be a nightmare in this area). On this occasion, we'd got just past Bourg Saint Maurice and had been sat completely stationary for well over an hour. Eventually, I heard on the radio that there was a broken-down vehicle blocking the road ahead and that it was grid-locked most of the way to Moutiers.
I decided to use a bit of local bike-shuttling knowledge, pulled a U-turn, headed back towards Bourg and dropped down onto the back road via Landry. Followed this through (moving at least, despite taking forever at each junction to get across the stream of ski traffic coming down from the resorts. This road follows the valley floor for about half the distance, then climbs up some hairpins, through Notre Dame de Pré and back down hairpins to the main road near Moutiers. It was snowing steadily and the back roads don't get so much attention from the ploughs! With full snow tyres, I was fine. Plenty of other locals, taxis, transfer companies etc. were going the same way. Unfortunately, there were a lot of tourists in hire cars tagging along! The up and the across bits were fine, but once we started going back down the steep hairpins, it was carnage. There were cars in ditches, cars in the trees, cars crashed into each other and one guy doing a proper Italian Job "I've got a great idea!" number. By this time we were following a bunch of late-teenage Belgian kids who'd clearly been allowed to borrow Dad's car for their ski trip. It was a Toyota Land Cruiser 4x4 kitted-out with what looked like full-on spiked mud tyres.
Eventually we came across a severely off-camber passage, covered in nasty-looking compacted snow and ice. Get past this and we were home and dry. Belgian Toyota went first - and slid straight off the road sideways, crashing into what was now a pile of other cars that had done the same. That's 4WD, spiked mud tyres and a legendary off-road vehicle. I was immediately behind in my 2WD long wheel-base Renault Traffic van. Proper snow tyres though.
We cruised it, no worries.
Got to the airport at 1514. My aunt & uncle's flight was at 1520. They let them on! They were passenger numbers 60 & 61 to board of a flight that was booked for over 120 people!