12SLIMITED

Whats up 7th Gen community! My name is Rob and I just leased a 2012 S with the Limited Edition Package. Ill have it for two weeks this Sunday and can definitely see myself buying out the lease...the car is just awesome! The one question I have so far is about tire pressures...after getting the car home I inflated the tires to the sticker recommended 33 psi cold. In 12 days I now am down to 31 psi cold on all four corners. Are these Limited Edition rims supposed to lose a tad of pressure? I traded in a 350z that would hold the same pressure for literally months at a time. Thanks for any input and will get pics of the ride up shortly!

lightonthehill

My rims have not lost pressure over short spans of time during the almost four years I have had my 7th gen. In 64 years of driving, I have found that ALL tires gradually lose pressure over longer spans of time - say many months.

It is also normal for tires to lose a few psi as the weather turns cold. When the temps fall fairly quickly from the nineties to the thirties where I live, that drop seems to reduce the psi in my tires by four or five pounds. This is something I watch for each fall.

Be sure and use the same tire guage, and hold it at the same angle each time, with the tires at somewhat the same temperature each time, otherwise you will not be making a meaningful comparison.

If I am measuring before the tires have completely cooled from driving (can take over an hour in some situations), I expect the psi to read higher than the true cold psi in the tires. So when I am checking the psi at a gas stop on a trip, my only purpose is to confirm that all four tires read the same psi, understanding that the reading will be above the true cold psi in the tires.

Nissan recommends 33 psi, but many here on the org have gotten better handling and control with a little more pressure. I carry 37 front and 35 rear, but I think 35 in all four tires might be the best compromise for most drivers, as that means we don't have to adjust the psi when rotating the tires between front and rear.

There are folks who swear by the use of nitrogen, which is less-affected by temps. But for someone like me, who is constantly adjusting psi in order to have my tires wear evenly, using nitrogen would require a trip to a nitrogen source every few weeks. I don't need that. Nitrogen also costs money, unless free nitrogen was used by the dealer as a sales pitch. The use of nitrogen also means that if you need air while on a trip, you have to leave the freeway and begin searching for a nitrogen source.

I think that as you continue to adjust and check your psi, you will find that it will fairly soon settle to where it does not change very quickly, other that when hot from driving or when the outside temperature changes quite a bit.

12SLIMITED

Thanks for the info. I live in south Florida and the temps did drop about 20-25 degrees last night so I guess that could be it. You are not the first person I have seen talk about the car handling better at slightly higher tire psi so I think when I wash it tomorrow night I am going to bump them all up to 35 psi

Amerikaner83

iTrader: (17)

you can go as high as 38 or 40 if you really want to... I go 38 in mine and it's perfect for me.

12SLIMITED

Does the quality of the ride suffer with your pressure that high? At 33 the ride was still good not overly rough or anything, which I'm not looking for! After driving the 350z for some years, I am done with an overly stiff and rough ride for a while!

Amerikaner83

iTrader: (17)

At 38 the ride is smooth as silk. At 40 it gets a bit bumpy and floaty...I sick to 38 mainly.

12SLIMITED

Awesome...thanks for the info I am going to try that!

vball_max

iTrader: (5)

as a rough rule of thumb, you typically lose 1 psi per 10 degree drop. If the temps dropped 20-25 degrees, it would make sense that you lost 2 psi.

lightonthehill

I did try 39, then 38 psi at times in the past, but found that this caused my tires to wear out in the center of the tread before they wore out on the shoulders, shortening the useful life of the tires.

This concentrated wear depends on ones type and style of driving. If your driving includes lots of fairly sharp turns at speed, a psi of 38 or 39 might be pefect. For mostly freeway driving, this high psi will shorten the life of the tires by putting most of the wear in the middle of the tread.

I measure and record the tread depth of each groove across the face of each tire every three months (easy to do in my heated/cooled garage), and that is why I settled on 37 psi in front and 35 in the rear. If I did mostly freeway driving, I would need to lower my psi in order to get even tread wear across the face of the tire.

The primary reason I keep a lower psi in the rear tires is because two-thirds of the weight of this car is on the front wheels, so raising the psi of the rear tires reduces the area of the tire in contact with the pavement, which slightly reduces braking effectiveness and slightly reduces control (less pavement grip) in sharp maneuvers.

Another factor in all this is equipment protection. When the psi in a tire is low, it can result in a pothole squeezing the tire to the point both the tire and the wheel are damaged. Likewise, if the psi in the tire is too high, it does not give the tire enough flexibility to 'give' when hitting a pothole, resulting in major damage to the tire. A higher psi also results in the wheels and tires transmitting more force and wear to the suspension of the car.

Every action we take has both intended and unintended results. Each person has to weigh all the factors and decide what is best for his situation. I have been driving since the 1940s (all tires had 'inner tubes' back then), and am still making adjustments as I find out things I didn't know.