Pontenza RFT in TN Winter?

[Bluesea Bimmer]

I have a Z-4 2009 Sport Package with 19 " wheels. Looking at my first Tennessee winter with the car. Running stock Bridgestone Potenza RFT summer tires.

We have almost no snow here -winters are mild - but we do have days that stay well below freezing.

Question: What is the REAL impact of cold on my summer tires? I've read all the information, but I ran the same tires on my prior 3-Series (moved here from FL and had no clue my tires were "summer only" tires !). I never noticed any handling issues with my 3-series in winter.

I have my husband's Subaru all wheel drive to use if any snow or rain is predicted in the winter months, but I wondered if anybody else has run the 19" Potenzas on the Z-4 in below freezing weather, and what the handling characteristics are?

Thanks in advance!

[jparnes1]

Theyre' called summer tires for a reason. They will lose tremendous amounts for grip in cold weather. Maybe you didn't notice that on your 3 because you didn't need to notice it (no need to break or turn severely) and you were driving from the south in warmer temperatures. You get snow in Tennessee? Maybe jsut some all seasons. Be safe.

[Bluesea Bimmer]

Thanks for the input. Actually, I moved from FL to TN 2 years ago and drove my 3 series with the Potenza summer tires for 2 winters in Tennessee, blissfully unaware that I had summer tires! I even drove them in a bit of snow ( 1 - 2 inches). I did not drive fast; I did not corner fast - normal driving in rush hour traffic.

Ignorance was bliss, I guess.

[mstevens]

The Potenzas are ridiculously bad in even very light snow or ice and, as noted, have poor grip even on dry but cold roads.

[dhplachy]

A little bit farther north than you and looking to put snow tires on my ride too since I've gone an loaned my other Bimmer (sedan) to my daughter who is in college.

From the literature, it seems that BMW recommends going down the the 17" wheel when using snow tires on the Zed so I'm not sure what that will cost to buy another set of wheels since mine has the 19" M wheels.

If there are any others that have done this on a 35is, I'd appreciate your feedback.

[mstevens]

Search for threads here about snows on a 35iS.

In summary, 17" wheels are very unlikely to clear the brake calipers. I do have an old set from my old Z4 that just barely fit, but nothing else I've found in that size does. That sucks since Nokian Hakkapeliitta R's aren't available in the US in a size that fit the 18" wheels on my current Z4 so I'm sadly stuck with Blizzaks. If you can find 17" wheels that safely fit your car, my recommendation is get them and pop Hakkas on.

Edit: did the search for you

http://e89.zpost.com/forums/showthread.php?t=462433
http://e89.zpost.com/forums/showthread.php?t=474248
http://e89.zpost.com/forums/showthread.php?t=415365

[nicknaz]

It is a big risk using full summer tires in the snow. stopping distances increase tremendously. There is a test somewhere (tirerack?) that showed by the time a car stops with winter tires the same car with summer tires is still going 20mph.

Switch over to winter tires...

17" wheel will clear since the Z4 35i comes stock with 17" wheels

I used the LM-25 winter RFT in Chicago and they were great. Still retained a crisp steering wheel feeling at turn in.

[mstevens]

Originally Posted by nicknaz

17" wheel will clear since the Z4 35i comes stock with 17" wheels

The OP didn't specify what model she has, so we don't know if 17's will fit or not.

[Bluesea Bimmer]

My 2009 Z has the Sport package with 19 inch wheels.

Based on the research I've done so far, sounds like I will go to 18 inch wheels and all season RFTs for winter (non snow) driving in TN.

Now I have to determine the most cost effective wheel/tire package.

Thanks to all who have responded so far!

[mstevens]

Originally Posted by Bluesea Bimmer

My 2009 Z has the Sport package with 19 inch wheels.

Still doesn't tell us what model you have. 30? 35? i? iS? The most pertinent issue is the size of your brake calipers, not the size of your current wheels.

[Bluesea Bimmer]

Car is a 2009 35i

(BTW - before coming to this forum to get info, I went to my local BMW dealer. They "never heard" of installing different tires for cold weather. After waiting about 10 minutes in the service department for an answer as to what the suggested wheel/tire combination was for my car for all season RFTs, I finally left without an answer. Sigh).

Thanks again for your help!

[mstevens]

Originally Posted by Bluesea Bimmer

They "never heard" of installing different tires for cold weather.

Scary.

When I picked up my first Z4, my dealer made me sign a statement saying I understood that driving on summer tires during winter was dangerous, even if the roads were dry.

[juhap]

On a related note...

[dhplachy]

Originally Posted by mstevens

Search for threads here about snows on a 35iS.

In summary, 17" wheels are very unlikely to clear the brake calipers. I do have an old set from my old Z4 that just barely fit, but nothing else I've found in that size does. That sucks since Nokian Hakkapeliitta R's aren't available in the US in a size that fit the 18" wheels on my current Z4 so I'm sadly stuck with Blizzaks. If you can find 17" wheels that safely fit your car, my recommendation is get them and pop Hakkas on.

Edit: did the search for you

http://e89.zpost.com/forums/showthread.php?t=462433
http://e89.zpost.com/forums/showthread.php?t=474248
http://e89.zpost.com/forums/showthread.php?t=415365

Thanks for the info. Mine is a 35is and what I was told by the Tire Rack folks is that the 17" wheels won't clear the calipers.

I've asked the dealer twice and still have not heard back. One would think that they would WANT to try to sell me some wheels and tires.

It was down to 35 degrees here yesterday morning so it won't be long before I'll be in real trouble if I don't do something soon.