Hi, I'm trying to find snow/winter/all season tires for my 911 Turbo. Seems like options are slim. Any ideas??

The summer tire specs are:

Front: 225/40/18
Rear: 295/30/18

Thanks for any ideas and help you have to offer!

 

I run 295 35 18 rears and 245 40 18 front with Continental DWS06 tires,, a little larger diameter but better ride and a little more clearance .
I am not a road racer , they are great in the cold and slight snow.

 

Start with Tire Rack.

Probably best to get a set of wheels dedicated to winter tire use.

It is very unlikely you will find real snow/winter tires in the same sizes at the summer tires.

Be aware what sizes you do find will likely not have the rear axle turning more revs per mile than the front axle thus the viscous coupling may not be operating at 100% efficiency. This is not a real problem as there is no useful torque transmitted to the front diff through this viscous coupling to make any difference in marginal traction conditions. Essentially in snow/on ice the Turbo is a rear wheel drive. (If you get stuck avoid spinning the rear tires. You'll just burn up the viscous coupling/front diff.)

In fact IIRC with some winter tire sets the front axle actually turns more revs per mile than the rear but these sets are factory sanctioned.

 

My snow experience seemed to indicate a full 4WD experience. In low traction situations, I found that all four wheels would spin - never just two. If you are getting the rear wheels spinning alone, you should check out your front diff - something is wrong.

 

^^^^^ this for sure, sizes and tire, for snow go blizzack's

 

Your experience is contrary to mine.

Even with summer tires driving in the snow I never managed to get the front tires to spin. And in one case this when driving east on I-40 in NM (some miles east of Albuquerque) with several inches of fresh snow on the pavement. Fortunately I had very new summer tires on the car and there was just snow -- no ice -- and no steep grades to climb nor sharp turns to make. The 40 or 50 miles of snow was about in the best place it could be for my Turbo. I just kept the speed down and 35mph and after an hour or so drove out of the snow and a few miles later pulled off the freeway to book a hotel room in Santa Rosa NM.

There are a number of videos of 996 Turbos in the snow and while the rear wheels are spinning like crazy the fronts are in some cases not turning at all. Videos of the 997 cars in similar conditions do show the front tires spinning. The AWD system in the 997 AWD models is a much better (make that real) AWD system than the one in the 996 AWD models.

In fact, when I was headed back east in the winter with my car the techs cautioned me to avoid prolonged spinning of the rear tires. This won't transmit any real torque to the front axle but it can over heat the viscous coupling. In areas where snow/ice are common it is not unknown for a driver to pull into the garage and get the car "stuck". With the front tires on the clear garage floor and the rear tires on snow/ice the driver might think the AWD will let the front tires pull the car into the garage. So he tries and the rear tires just spin and the fronts don't do squat. All that happens is if this is kept up too long a very expensive front diff is ruined.

They also cautioned me against if I got the car stuck to avoid spinning the rear tires. The tires won't grip and the fronts won't pull the car out of trouble.

According to Porsche it takes approx. 150mph for 40% of the engine's torque to be transmitted to the front axle. The minimum is 5% but I do not know at what speed this occurs. And it takes some time before the viscous fluid is at its operating temperature of over 300F. In cold weather a low speed operation it might not get hot enough to transfer any torque. Maybe this why there appears to be no concern on Porsche's part regarding the factory sanctioned winter tire sets which "violate" the typical difference between rear tire revs/mile vs. front tire revs/mile the summer tire sets have.

 

The symptoms you describe sound like the front diff is not functioning properly. My experience on snow and ice is that the car handles like a tank. I once waited 10 minutes while a 4WD crew cab pickup truck with 6 people on board tried to climb a 40% grade covered in snow and ice. He finally backed out when he couldn't get more than a couple of yards up the hill. Once he was clear I pulled into position at the bottom, looked and him and smiled, and drove up full speed without slipping at all.

On the other hand, I had a problem last year with the front diff and removed it for a few months while I waited for it to get repaired. It was absolutely useless in the snow. So, I know from experience that the 4WD on the 996 TT is everything you would expect from 4WD as long as your front diff is working properly.

I would question who you talked to at Porsche that would suggest the diff only functions fully at 150 mph. Does that make sense to you? I understood that the distribution was altered by the amount of rear slipping and not by speed. Unlike the 997, the 4WD on the 996 is always on.

 

This past winter I decided to start daily driving my 996TT. I had no issues even in snow storms in Denver. The car is easier to get going than my other DD, a FWD Acura TL Type S with snow tires. No trouble getting up the driveway. Having driven previous RWD performance cars in the snow (Trans Am, Mustang Cobra, E39 M5, Infiniti G37), I can say the 996TT has far superior traction. How much is having the engine in the rear over the driven wheels vs. the front axle helping, I can't say - but it does really well.

I used a set of OEM wheels with Blizzaks of the following sizes:

F: 225/40-18
R: 275/35-18

These were the recommended sizes for the stock wheels by TireRack back in the day when these tires were still available. Looking on there now, there are Blizzaks (and several other winter tires) available in the sizes but you'd need to do different models front and rear as there isn't one available in both sizes. The rears visually seem to be very stretched, but the specs do line up as the max wheel width they can be run on. The car actually drove fine, too, even on warmer dry days - no spinning of the tires, no 'rolling over' onto the sidewall - it felt perfectly fine.

by https://www.flickr.com/photos/kfanciu/, on Flickr

by https://www.flickr.com/photos/kfanciu/, on Flickr

by https://www.flickr.com/photos/kfanciu/, on Flickr

by https://www.flickr.com/photos/kfanciu/, on Flickr

by https://www.flickr.com/photos/kfanciu/, on Flickr

Hope this helps as an option for you.