I have the stock RF Conti Contact 4X4 SSR tires - I don't like the tires. So I have made a decision to get out of run flats entirely by:

Step 1) Installing a non RF dedicated winter (emphasis on snow) tire on my BMW 19" 335 wheels

Step 2 - this Spring I plan to purchase a set of (gorgeous - yet to be determined) staggered 20s and install the best (within reason) non Run Flat summer tire I can find

So, to get Step 1 going, I just ordered a set of Vredestein Wintrac 4 Xtremes in 255/50/19 to be installed on the BMW 335 Wheels. Note - Ilive in Colorado and plan to go skiing as often as there is good snow and funds permit!

Before making my decision I considered:

Hannkook I-Pike (have these on my 2012 F250 Super Duty and they are great)
Michelin X-Ice XI-2
Pirelli Scorpion Snow & Ice
Blizzak LM-60
Nokian Hakkapeliita R

I chose the Wintracs because it is my hope they will offer better than average handling with the snow & ice capabilities of a true snow tire. We shall see!!!

I will have about $1,200 invested after mounting and balance - not the cheapest setup, but hey, this X5 wasn't inexpensive, and for a few hundred dollars more, I want to wring every bit of enjoyment out of the car that I can!

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2011 X5 Xdrive50i Sport Package AD
2013 Touareg TDI
2012 Ford F250 Super Duty Powerstroke
1997 BMW M3 Sedan
1995 BMW 540i 6 Speed

Retired:
2008 Acura MDX (good car - yawn)
2002 M5 (I will miss this car forever)
1999 M3 (fun car X2)
1992 325IS DINAN (fun car)
1987 325IS (fun car)
1986 325IS (fun car)