Should I go by the recomended PSI on the tire or on the label inside the door?  Also, does it matter to have more or less air in the tires when driving in snow?  Thanks for the advice.

Use the pressure rateing on the tire. It will tell you the max rated pressure- lets say 35 psi- So you would run the tire @ around 30 psi. The label on the door will give you the best ride for the tires that came with the car.

For snow and winter conditions run the tires at the same as you would for the summer. It is more important to have the correct type of tire.

Just make sure to set them under the max psi thats on the tire. What kind of vehicle/tire sizes?

The pressure on the door is for the best tire wear.  The pressure on the tire is the MAX for that tire, and dosn't mean much.  30-35 PSI is good.

Quoted: Should I go by the recomended PSI on the tire or on the label inside the door?  Also, does it matter to have more or less air in the tires when driving in snow?  Thanks for the advice.

Didn't know you guys in Alabama got snow.  Kidding!  Go by the recommended PSI on the door for general use.  If you have to drive in something slippery or where you need extra traction, a little less air pressure is better.  That allows the tire to spread out and get more contact with whatever you're driving on.  MJD

Quoted: The pressure on the door is for the best tire wear.  The pressure on the tire is the MAX for that tire, and dosn't mean much.  30-35 PSI is good.

No, the listed pressure on the car is for handling with OEM tires.  It can differ with aftermarket tires.

The tire construction dictates the maximum pressure and load it can carry.

Don't worry about measuring the PSI.  Just add air until the tire looks round, get rid of the sag between the rim and the ground.  You will get better mileage, but the ride may be a little rough.....
On second thought, there is probably someone out there stupid enough to try this.  It isn't a very good idea.

I usually go with the tire pressure stamped on the tire.  The reason is that the higher tire pressure will present less rolling resistance, therefore higher gas mileage and longer tire wear.  I watch the tires very carefully for abnormal wear, over inflated tires will wear on the outside edges of the tire because this maybe too high and I adjust accordingly.  Also the vehicle will ride a bit harsher or be a bit bouncier.

Quoted: Quoted: The pressure on the door is for the best tire wear.  The pressure on the tire is the MAX for that tire, and dosn't mean much.  30-35 PSI is good. No, the listed pressure on the car is for handling with OEM size tires.

Obviously it'll change if you go from 195/60R15s to 225/45R17s, but it should not make a difference whether they're Continentals or Michelins.

Quoted: Should I go by the recomended PSI on the tire or on the label inside the door?  Also, does it matter to have more or less air in the tires when driving in snow?  Thanks for the advice.

If you are using the same size tires as the ones that came on your car, use the information on the label inside the door, as that is what the entire vehicle is set to use. If you are using aftermarket wheels with a different profile than stock, then you have to use a different pressure.

Quoted: I usually go with the tire pressure stamped on the tire.  The reason is that the higher tire pressure will present less rolling resistance, therefore higher gas mileage and longer tire wear.  I watch the tires very carefully for abnormal wear, over inflated tires will wear on the outside edges of the tire because this maybe too high and I adjust accordingly.  Also the vehicle will ride a bit harsher or be a bit bouncier.

Use what the tire says; mfr's website may have more detail.  I generally go for 5-10 psi under, tires are LT's used on a Suburban.

Find an accurate pressure gauge.

Over-inflated tires wear the center tread section, under-inflated wear the inside & outside edges of the tire.  I would not inflate a tire to maximum unless the car/truck was loaded to max weight...maybe better mileage, but wicked fast tread wear if the vehicle is lightly loaded.

-hanko

Quoted: but it should not make a difference whether they're Continentals or Michelins.

Yes, it will. Different brands of tires are made with different compound formula's, no two brands are ever the same.

If a tire had use Deisel fuel in vehicle, would you do it?

Tire mfg's KNOW what their tires should run at, go with that PSI, Not under not over.

I've never seen a tire with a recommended pressure -- only a maximum safe pressure.

Go by the pressure in the door panel.  If that pressure is higher than the max pressure on the tires, get beefier tires.

I usually run about 4-5 psi higher than the door panel because I think the listed pressures are slightly biased towards a smoother ride.  A little more PSI will give you better mileage.  But don't go too high, or you'll have less road grip and uneven tire wear.

Make sure you measure the pressure while the tires are cold.

Remember the fact that the weight rating on the tire is determined at the MAX inflation pressure. Running it even 10% low will reduce the weight rating by at least 10%, 20% under inflated drops weight rating by around 25-30%...for a max inflation rating of 35 PSI, 10% means only 3.5 pounds under or 31.5 psi... For those running 10 psi low on a 35psi tire, you should realize that you've probably lost about 40% of your weight capacity and are probably in the negative region...thus even with the vehicle totally unloaded, you're riding on overloaded tires. (of course if it's an 80 psi rated tire, you've only lost maybe 15% of your weight capacity )

Do what ya gotta to keep the tread wear even, but if you're carrying a heavy load, pump the tire up to full rating.

The above numbers come from some research I did for a presentation and in part are based on NHTSB studies.

On my truck, I run the max pressure for my LTX's and have seen NO funny treadwear patterns, but I keep a good watch on them just the same, this is over the last 50K miles BTW

Oh yeah, use a quality tire guage. I've had some frightening results from the .99C specials...as in having one tire that was 20 psi OVER rating and another one on the same truck that was 10 psi UNDER...scared me enough to buy a decent guage.

The book answer to your question is to always go by the lable on the door if you're using OEM tires, however, you'll always be safe using the tire rated pressure. The numbers on the door are generally there for best ride and even the owners manuals will tell ya to adjust for heavier loads usually.

Good tire pressure advice.

www.tirerack.com/tires/tiretech/techpage.jsp?techid=1¤tpage=33

Quoted: I usually go with the tire pressure stamped on the tire.  The reason is that the higher tire pressure will present less rolling resistance, therefore higher gas mileage and longer tire wear.  I watch the tires very carefully for abnormal wear, over inflated tires will wear on the outside edges of the tire because this maybe too high and I adjust accordingly.  Also the vehicle will ride a bit harsher or be a bit bouncier.

No, high pressure wears out the middle of the tire!!

Ok.  Well. The tires on my truck are OEM.  They say the max is 45 Psi.  My label says I should run 29 Psi.  Since I've had the truck I run 35 to 40 PSI.  The only wear is feathering from the tires on the front.  
I'm just trying to figure this stuff out.  So.  It seems like ya'll are saying I should keep em at what I have been doing.  Right?  How about if I start loosing traction?  Should I air down?  My truck is not that heavy.  Its a little Tocoma.

The pressure given on the side of the tire is the maximum the tire is designed for, it's not what all vehicles should use.

The door sill is the pressure to use, as long as the tires are anywhere near the stock size and you aren't regularly doing anyything like occasionally carrying extra-heavy loads or pulling trailers.
~

I keep all tires on my car and wife's car pressured to just under the max pressure indicated on the tire.   My truck tire says 35PSI max so I keep it at 33 PSI.  My wife's tires says max 40 PSI so I keep it at 38 PSI.  I have always done this and I have gotten good use from tires.  I noticed that all my tires wearout evenly across the tread.

My truck tires  currently have 63,000 miles on tham and I think they will last another 15,000 miles.  My wife's tires usually last 60-70,000 miles.  
 

Quoted: Quoted: I usually go with the tire pressure stamped on the tire.  The reason is that the higher tire pressure will present less rolling resistance, therefore higher gas mileage and longer tire wear.  I watch the tires very carefully for abnormal wear, over inflated tires will wear on the outside edges of the tire because this maybe too high and I adjust accordingly.  Also the vehicle will ride a bit harsher or be a bit bouncier. No, high pressure wears out the middle of the tire!!

I worked at a used tire place for awhile.  Great place... the owner had a kickass business.  Collect all the used tires, sort out the shitty ones, they're sold to Cleveland, the not-so-shitty ones are sold to Mexico and the decent ones he re-sells to his customers... until the guy died.

You're best off somewhere between the two ratings.  Going with the max pressure listed on the tire is just fine and you will only cause the center of the tire to wear out prematurely if it's either a really wide tire with low aspect ratio, or you're running really, really high pressure.  I'd say almost 50% of used tires have significantly more wear on the outside of the tread than the inside of the tread (underinflation), probably less than 5% are worn significantly more on the inside than the outsides (gross overinflation).  Overinflation is not as big of a problem as underinflation (within reason).  Though, if I were to go out on a limb, I'd guess that 75% of the underinflated tires come off of a woman's car... my sister never checks her tire pressure and busted two rims with six months.

I always run a couple PSI below the tire's max rated pressure, to compensate for hot days when the heat will raise tire pressures.  Monitor your tire wear, if you notice they're wearing out faster on the inside, lower pressures... wearing faster on the outsides, raise pressures.  The lower the aspect ratio (fat, wide tire), the more impact air pressure has on the wear pattern.

Also... personally, I feel lowering tire pressure of radial tires for winter traction is a bad idea.  You will likely wear out the sides of the tread very quickly, and you will get piss-poor fuel economy, with lots of additional wear & tear on your drivetrain.  I feel the better option is weight over the drivewheels, or dedicated snow tires for the winter.