Winter Snow Tires PSI ?

[Wausau 911]

I saw a TSB stating rear should be 39 rather than 42. I am running Blizaks. Not sure the TBS was for a C2 though. What is the consensus for correct PSI front and rear?

[JasonStern]

While not a 996-centric answer:

http://www.tirerack.com/winter/tech/techpage.jsp?techid=168

[Mijostyn]

Wow Jason, that Tire Rack article is out to lunch. The right tire pressure is that at which the tire wears evenly across it's tread. That is also the pressure at which the tire develops it's maximum effective contact patch and thus the maximum lateral load capability. To some the handling may feel better with higher pressures as the car will be stiffer and sharper but in reality if you skid pad test it it will break loose earlier.

The right tire pressure is a moving target. It depends on the stiffness of the tire across it's tread, the width of the tire and the weight of the car. Always start with the recommended Summer tire pressures. If the snow tire is narrower than the Summer tire back off on the tire pressure 2 psi for every centimeter narrower to start. Check your tread depth at both edges and the center when the tire is new and every 1000 miles and keep a journal. Use a tread depth gauge. They are dirt cheap. If the tire is wearing faster in the center back off 2 psi at a time until the tire is wearing evenly.

Trying to make winter tires handle better is an exercise in futility. They are not designed for that. They are designed to run at colder temperatures and stick to slippery, snowy roads. Summer tires = stiff broad tread blocks with few snipes. Winter tires = numerous small flexible tread blocks with lots of snipes. Snow tire tread compounds are designed to remain supple at low temps. Summer tires are at their best when they are almost worn out. You can run them down to 3/32 just fine. Snow tires need to be replaced at 6/32 as they start loosing their grip in snowy conditions.

[Dennis C]

I use the same pressures for winter tires as my summer tires.

[narkose]

Interestingly, my owners manual supports what Dennis C stated. Same pressures: Summer or Snows

[P2C4]

For the last 9 years (and over 140K miles) my daily drive has been 1999 C4.  I live in Sandy, Utah, near the mountains (15 minutes from Snowbird), and somes take this car up skiing (skis inside the car always). It does well in the snow, with 17" Blizzaks during winter months.  I use no more than 36 front 38 rear, and a pound or two less if there is a fresh foot of snow to plow through.  Sunner with Michelin Sport Cups 33 front 35 rear, since it gets over 100 degress most of July.  Too high pressure especially on winter tires, on a freeway gives you the feel of fishy tail as you change langes.  Too high a pressure on summer tires and you feel too much of the road imprefections, for comfort.  Standard suspension.