heya! i was shocked how much difference air pressure makes in this car!

b4 i was getting arround 22 MPG city/ hwy @ 40ish psi

so i cranked it up to 55 psi now i average 24 Mpg over 2 tanks so far
(but at a loss of traction on corners) but no biggie

anyone else?

 

please dont do that!!! Im no tire specialist but I think 55psi in our tires is almost not safe man. I was told the reccomended was 35 cold 40 psi warm. If you want better gas mileage on the highway, I have a interesting method. Ive tested it numerous times. Turn on you AC. Everytime I have my AC off going down the highway at say 65mph, flat surface for about an hour I get 28mpg, tuen AC on, keep same speed on flat raod for an hour again and watch my gauge slowly creep to 30mpg. Kinda wierd. Most cars get worse mpg with ac on. BEN

 

hmm well on my tires it says 44psi max, but with highter pressure is less rolling resistance i wouldnt go any higher tho.. there pretty hard riding

as far as the a/c goes ill give it a try but yea it dont make sence since the a/c compressor is a Drag on the engine!!
(why dont they make those electric too as well at the P/S pump heh)

thanx: for tip?

 

You will also wear your tires out much faster, the handling will be much worse, etc. You have basically distorted the tire so it is only riding on the very middle portion of the tire. You're tires will probably last 1/2 as long so you'll spend $1000 on new tires to save $60 in gas.

 

aww man yer takin the air outta my high.. but yea you guys are right ill lower them to 44ish again,

hey hookieZ i love that break caliper in yer wheel pic i want to do that!

 

I'd lower them down to 35'ish, I believe that's the optimum pressure to get even wear. I've kept mine there throughout and have gotten very even wear across the profile of the tire. I have one tire that has averaged about 38 and the middle is noticeably lower in thread depth than the outside just from that small increase.

 

hmm intresting lots of good ideas
i was thinkin they would have more wear on the insides due to the slight cant inward??

and that higher pressure would lessen that ..

 

That maximum pressure stamped into a tire is the max for a given rated load. Since those tires are not made specifically for the Z, that does not mean that you can put that much air in them safely. Nissan has already gone thru the trouble of calculating the correct air pressure based on the tire rating and the weight of the car, then factoring in performance, handling, ride quality, tire wear and safety.

 

very bad idea. say a prayer before driving in the rain up there in OR. your tire is now bowed out, with the inner and outer edges having less contact with the ground than the middle portion, like you're rolling on marbles. My dealer told me i could increase the cold air pressure to 40psi, but even that small increase wore out the middle of the tire faster than the edges. go by the book on this one, for your and others safety.

 

yea i decided to do that, thanx)

 

The only time you should inflate tires that high is at an auto-x. And even 55psi is high.

 

55psi is ridiculous. Imagine a tire blowout at high speeds? That would really suck...

I drive around town with 36psi cold. They get to 40 when hot.

 

they head up THAT much?? the most i saw bet hot and cold is about 2 PSI

As far as auto-X im going to LOWER it to 35 because i have found that using the high pressure i loose traction Much easier

 

You should only be raising the pressure that high in auto-xing on the front tires. The idea is to prevent the tire from rolling over onto itself, by stiffening the sidewall. You should fill it to about 46-48 PSI, do a run, and see what they heat up to. Fill or empty as necessary. 35PSI it too soft to be auto-crossing on, especially in the fronts.

 

Oh, I should have clarified. If i'm leisurly drivin around town the psi won't go up more than 1 or 2 psi really. If I sit there and do launches, and do some really hard country/highway driving, i've had my psi up to 41. The temperature still stays around the low 40s where I live at night. My tire pressure on a summer day is probably 37. Colder nights it is at 35-36.

I havn't auto-xed my car much, so i don't really know the optimal tire pressure setup. I didn't bother chalking my tires to see if I had any sidewall flex.

 

Don't you think 48psi is a little much? As I stated before, I havn't auto-xed my Z much, so I am not really sure. That seems high though.

So what kind of a differential in tire presure do you run from front to back? It would be interesting to try some good settings out next time I go.

 

This was auto-xing on my Prelude, but the settings I used were:

Approx. 46-50 PSI semi-warm in the front. Once heated, I would keep them around 52 PSI.
Approx. 38-40 PSI semi-warm in the rear. Once heated, I would keep them around 42 PSI.


I also had an adjustable suspension, so I cranked the rears to 13-14 out of 16 and the fronts to 11-12 out of 16.

I haven't auto-crossed since October of last year and keep in mind these numbers were on a FWD car. I don't have my Z yet and won't have a chance to get her out to the auto-x field until next month sometime most likely.

 

Aerodynamics comes into play if you have the windows up.

 

With a stock setup, I would probably run a lower pressure in the front to make it handle more neutral. Too much would probably induce oversteer. I think I remember reading that given the same car and the same track, that understeer gives you a faster path than oversteer.

 

Yes it would, especially in a FWD car. But I ran on those settings and for the most part they worked really well for me. Don't forget the suspension settings come into play as well in helping to neutralize the balance of the car.