This thread is more for discussion and any factual opinions everyone has.
me and the boys at work (truck mechanic) have been debating for almost a week now on tire pressure.

Most of the old boys say you should set the tire pressure by the max cold PSI marked on the tire. (mine say 44PSI)

Their argument - The tire manufacturer knows best what the tire PSI should be, also they believe you'll achieve better fuel mileage and better tread wear.
(Although it's proven that only about 5% of the vehicles weight is on the tire itself, the rest lies on the air IN the tire)

I personally think that you should always set your tire PSI by the vehicle manufacturers specs (which is 32PSI Front, 29PSI Rear on my SE). IMO the car manufacturer spent millions of dollars designing the car, right down the the ideal tire size and pressure to achieve the vehicles optimal performance, ride, and wear on tires, suspension, brakes, etc.
The only reason i could see to ever change / alter that stock PSI is with a different tire/wheel on the car / if you have lowered the car. Either way the pressure wouldn't be more than a few PSI from stock reccomendation.
Also over inflated tires ( would be approx 10-14PSI OVER if set by my tire max cold PSI) provide less traction, braking, and can't conform to road irregularities as well (jittery ride). When overinflated the tire rides more in the center than evenly across the tire.

Just wondering what you guys set your tires at/your opinions on the subject, I have a bet on with the one guy at work but although all the searching I've done has resulted in my opinion being correct, he still disagrees, I dont know how to prove it right now it seems like more of a matter of opinion.

 

I set mine to vehicle specs rather than tire specs. When i did set mine to tire specs (about 45psi) the ride was extremely rough and the tires felt way over inflated IMO.

 

Tire pressure is dictated by the load placed on it. The load comes directly from the vehicle weight, which is printed on the door jamb sticker. That's the pressure to use. The pressure on the tire is a *maximum* which really determines how heavy of a vehicle is can be safely used on. The tire manufacturer has no idea what weight it will be loaded with.

The sticker pressure is a baseline for an unloaded vehicle. You can add 3-5psi all around if it's heavily loaded or regular highway travel.

Running your tires at the rated maximum can actually prevent a proper contact patch from forming against the road. First, you lose a lot of grip, and second, you can get uneven wear. It's really a bad practice.

Dave

 

even though the car manufacturer did spend millions of dollars on designing the car down to the tire, you have to also keep in mind that they are trying to spend as little money making the car as possible to yield greater profits. not that the amount of air in a tire cost them more or less money, but you have to keep in mind that not every part of a car is designed to perform as well as it could.

 

daves right. if you look on some of the tires themselves, it says ex: 44 (max psi). i usually go 80%-85% of what the max is. currently, the front is set to about 38, and the rear is set to about 33-35psi.

tired this out in the auto cross and got horrible results in my opinion. it was understeering like crazy. i could feel my sidewalls slippin out if thats the correct term.

 

Autocross is a whole different game. Rule of thumb, show up for autocross with +10psi in all corners, which would be around 40psi for a Maxima. But the issue of understeer is bigger than pressure - the challenge really belongs to the driver to keep as much weight on the fronts while cornering as possible. Most FWDs that are set up for maximum oversteer can push if the driver's inputs are not appropriate. It's not easy to do, so don't feel humbled if you're pushing like crazy all over the course. Driving FWDs fast is a special skill.

Ok, I've thought about it and kept it in mind. I still don't see why it changes the cost to use a lower tire pressure. If the OEM is skimping, it's on the tire itself. And that's irrelevant since the typical maxima enthusiast is (should be!?) smart enough to buy the best tires for their driving usage.

OEMs do tend to bias the pressure on the low side to improve drive comfort, since that's vitally important to making a new car sale, and they don't outfit new sedans with good sticky tires. This much is well known, but the pressure still affords excellent performance. But the fact is that if you put high performance tires (say Kumho V710s) on your car the best place to start tweaking your tire pressure for track use is still around the sticker value. Then you can rely on pyrometer readings and scrub wear to determine what camber angles and pressure is perfect for that set of tires.

Autocross is always a special case in tire pressure because the runs are so short the tire never gets hot and so you have to have your pressure set higher in the first place. The door sticker value works for street and track use because it allows for the normal heating of the tire and associated increase in pressure (hot pressure). The OEM is usually remarkably accurate in their recommendation.

Dave

 

what tire spec was 45psi? many tires I've seen have a Max load of 44/45 psi, but you always inflate to the vehicle specs.

I usually inflate a few psi over manufactures specifications, save on gas economy and ride is still comfortable

 

sorry typo on my part, i meant to say max load of 45psi. (Kumho ASX's)

 

Well put.
Only thing there I would disagree with from my knowledge would be increasing the psi for highway travel, where centrifigal force is forcing the tire to 'stretch/expand' out and causes a 'thinner/smaller' footprint, in such a case I would reccomend a lower pressure to compensate. Auto X is better at higher PSI cause you dont as you said reach high temps due to short runs, but the force exerted on the tire is more often to the side rather than centrifigual.

 

I recommend using nitrogen to keep the air regulated best. Just don't smoke and fix flats.

 

I keep mine at 35 all around

 

I keep mine at 35 too, Nitrogen is an inert gas so smoking should have no effect on it.

 

There are so many things wrong with this post.

What you are referring to is Nitrous oxide. Nitrogen dioxide is a fatal air pollutant. Nitrous oxide is the oxygen-rich gas used to boost performance.

On top of that, neither Nitrogen dioxide nor Nitrous oxide are abbreviated NOS. NOS is a brand name. Nitrogen dioxide is abbreviated NO₂ and Nitrous oxide is abbreviated N₂O.

Finally, Nitrous oxide is non-explosive. Its only purpose is to add extra oxygen for burning.

Oh yeah, blue smoke means you're burning oil. Have fun replacing head gaskets.

 

Putting all mistakes about Nitrous Oxide combustion aside, the most important error of this post was overlooked: nitrogen DOES expand with increasing temperature.

The real reasons to consider nitrogen can be read here:
http://www.getnitrogen.org/pdf/print...w%20071904.pdf

Dave

 

Your right I wrote Nitrogen dioxide, I meant Dinitrogen oxide -my bad guys.
1st -Yes I know it's oxygen-rich this is why it is used to boost performance because the oxide delivered via an inert gas nitrogen combusts aiding fuel for combustion thus increased hp. I said NOS because that is what people commonly know this gas to be, they tend not to use technical terms.
2nd -Nitrous is explosive atleast the oxygen molecule by its self is when it comes in contact with oil, this is why with a blow torch your warned not to lubricate the threads- this was my reasoning but since it was combined with nitrogen it would make it stable- my bad again.
3rd - and yes blue smoke can mean your burning oil, however if my head gaskets were leaking it would most likely be white smoke.
yeah nitrogen will expand but not to the levels comp air will <my bad for not clarifying.

 

I'd put nitrogen in my tires without a doubt if there were any place around here I could get it. I've asked the boys at the race car shop but they wont let me lol boss is a **** lately. Shytty thing is I have 1 tire leaking slowly I'm filling it up once a week. I'm curious if a standard guage would work the same with nitrogen, I assume it would. And would you want the same pressure in the tire, Nitrogen is lighter correct?

 

If you have a Costco's near you they should have nitrogen- mine does, anyways sorry about the bad info had my head up my a$*, gonna edit post.

 

costco isnt that close to me but i'll check it out I'm gonna do some research on it, but not gonna bother with the nitrogen until I get new tires cause i have a leak, that'd be a pain in the A$$ to refill every couple weeks

 

i also have the same question. right now i have my fronts at 38 and the rears at 32 and i squeel around every corner even at 5 mph. i have no i dea whats wrong ive tried as low as 29 in the fron and the correct vehicle spcs 32 in the fron and 29 in the rear and its just annoying. i do need an alignment but could that be why im squeeling so bad or is it just the tires> they are new tires as well which is why i am confused. can anyone help with that?

 

My 95SE calls for 33 front, 32 rear.

For about the past two years, I have been overinflating to 36 front, 35 rear in the interests of better fuel economy and longer tire life, possibly at the expense of a slightly firmer ride which I don't even notice now.

Remember to check tire pressure regularly. In colder climates, in the winter, radial tires lose about 2 psi per month.

 

tire life will decrease on an over inflated tire, not to say 36 is really over inflated, but wont increase your tire wear. Tjires that are inflated over the reccomended pressure wear quicker,
although it is good to note that underinflated tires wear much quicker than overinflated tires. and fuel economy would only increase at a higher pressure if you do mainly city driving.

 

Which wheels are squealing? Squealing at 5mph suggests scrubbing and really crappy tires.

Run 33/32 and take it to the alignment shop. Explain the noise. They should be able to figure it out.

Dave

 

I do 30-32psi all around on my 99 SE. I usually drive alone mostly so I don't worry about extra weight.