Xphstos

Had a quick question. Have snow tires for my A5 and was wonderng what the correct tire pressure should be. I have Dunlop SP Winter Sport 3D, the tire says 50 psi which seems high when I look at the existing tires it mentions that I should have 32 psi.

Mcqueen

I have the same WinterSport 3D's and I think what they say on the sidewall is "Max pressure 50psi"

I've been consistently using the pressures listed inside the driver door jamb. I think something like 39 up front, 36 in the rear (I'm going from memory) for my S5 - which might differ for the A5.

Tifosi

Use the same PSI as listed in your OM or on the door frame. You can increase it by 2 psi or so if you wish.

Xphstos

Thanks that is what I figured appeciate the quick responses.

elf_cruiser

For deep snow (> 1 ft) or on days where you just got a fresh dump, decrease pressures to 20-25 psi for better flotation and traction. Every little bit helps...

IAS5

actually, it's the other way around. Increase pressure a bit to reduce contact patch size, and increase lbs/sq in on the tirepatch. this INCREASES traction.

that's why the recommendation to go with a skinnier tire in the winter.

JBDinTX

Run pressure on door jam not side wall. Tires are made to fit many cars and they state the max pressure for that tire. I always run per mgf specs.

elf_cruiser

Actually, it's the other way around...
What you described is proper for ice, not snow. There's a difference
The best thing you can do in deep snow is to try and float over top of it. Key word is "try"-

IAS5

looks like we'll have to agree to disagree here. Lived in snow all my life (not trying to suggest you haven't, but have 30 years of dealing with it...), and to get the effects of lowering pressure, you'd have to reduce it much more (to less than 10 lbs) than you suggest to get anywhere near the "floating" traction you describe. The inherent risks of doing this is losing stability due to softer sidewalls, and damaging rims if you hit potholes, curbs, etc., that are hidden by the snow. As you said, you are probably not going to "float" a 3800 lb car anyway. They do not become snowshoes. This applies to rain and snow. This isn't sand.

Increased pressure (just to cold max pressure- nothing more)allows one to cut through the snow to increase pressure on the surface area, and give you traction. Less/no risk of stability loss to sidewall flex, and traction increases. The argument many have is that by increasing pressure, you do go deeper, possibly getting hung up on the snow. if you did, i would guarantee you that you would also if you lowered pressure. I've tried these pressure techniques both ways, and increased has always worked better.

Regardless of the technique, a foot of snow will eventually hang the car up on the axles, and you're done (if it is a heavier snow)

my .04 (adjusted for "cost of living")...

elf_cruiser

I agree with everything you just said. Haven't dealt with it all my life, but lived in AK for a few winters. Good to be in AZ now...

Notice in my first post that I was referring to "deep snow", and yah - trying to drive any of our cars through deep snow is challenging, and requires a lot of momentum to stay on top, regardless of tire pressure. I've driven through 2+ ft deep snow in an F350 with street tires aired down to 10 psi(still got stuck, bitch was too heavy), a B5 S4 with hakkepelittas at 15 psi, and a rockcrawler with 42" swamper tires at 3 psi. Which one ya think worked best?