Tires: Snows on front - Summer on back, mini cooper clubman, emergency maneuvers

Question
Hi Barry,
I've read a lot of your answers and you do indeed seem like an expert, so I thought I would ask you a question I have. The car is a 2009 Mini Cooper Clubman. The Continental tires that came stock are already showing wear on the front (evenly) after 14K miles and they suck in the snow. We want to put snows on the front and the Cooper dealer is telling us that we have to put 4 snows on otherwise we will have trouble. If the snows are the exact same size as the back (originals) why can't I do this? I really don't see the reasoning of having snows on a non-driving axial (the back). If the tires are the same size I assume I won't have trouble with the tire pressure alert system. Also, the original tires may be run flats in which case I would be mixing regular tires and run flat tires. Is that ok?
Thanks in advance!
Pete, Woodstock, NY

Answer
Pete,

Mixing Run Flats and non-runflats is not a good idea.  The best situation is where all 4 tires are exactly the same, including the amount of wear.  The more different the tires are, the likely there will be stability problems for the vehicle.  This usually shows up in emergency maneuvers.

But there is a bigger reason to use 4 winter tires.  The theory is that while it is important to have traction in the front end, it is even more important to have traction in the rear.  Otherwise, you'll spin out - which is a situation almost impossible to recover from.  When you lose traction, you generally get traction back when you slow down.  It is better to be pointed the right direction, than going backwards.

The basic principle is "Best Tires on the Rear" - and the shorter the wheel base, the more important this is.

Here are some video's that illustrate the point:

http://www.youtube.com/watch?v=gSz7cm6MwH0

http://www.youtube.com/watch?v=EdtAm7RsTmE%26NR=1