SidViscous

Well on my last trip to Montreal I stopped into the Local Greased Monkey for an Oil change. The guys were all excited to see a Porsche and were very friendly. One guy asked if I wanted them to do Tire pressures. At first I said no. Then I said what the hell I'm going on a long trip. Might as well check them.

Well on the way up she had less than the expected feel that I have become accustomed too. At first I blamed snow. But really there wasn't that much on the road, just windswept.

So then I blamed the wind. However, the on the way back it was still there with much less wind.

Been meaning to go check them but been very busy.

Finally made the time.

Front Driver 29 psi
Rear Driver 36 psi

Front passenger 36 psi
Rear passenger 29 psi.

Now I'm not sure, but I think this could explain my handling difficulties <img border="0" title="" alt="[Wink]" src="wink.gif" />

Tremelune

I've never noticed a huge change in handling in around town driving from tire pressure changes, but I'm not too sure what I'm looking for.

I run 36psi all around.

Scootin159

I run 30psi all around, but I think 29/35 is what's suggested.

SidViscous

Try running what I had. Completely wacky. You would notice that change.

Suspect you both would feel a difference going to the spec.

36 all around gives the fronts not enough bite, 30 all around gives the rear more float.

Dave in Chicago

I agree. I notice if one tire is off by 2 or more pounds. Driven regularly, the 944 is quite communicative to the seat of the paints and steering wheel.

Jerad

Yet another good reason to never use one of those oil lube places!

I think those types of tire pressure would really screw up the handling and balance of the car. I know some guys run the same pressure all around, but what if you have 7s in front and 8s in rear, should you run the same or different tire pressure? What about if the widths are the same front and back, i.e. cookie cutters, would you run the same tire pressure or different?

Tom

The recommended pressures are the same for 15", 16", 7x7 or 7x8. My experience has been that I get the best feel (less plow) running about 6 lb more in front. On the street I usually run equal pressure as the weight distribution is roughly 50/50. Within reason the effect of higher pressure is to increase precision at the expense of harshness. You do not really lose that much by softening the tire pressure a bit for a better ride. There is also a lot of variation with what makes different types of tires happy.

Brian S.

I would like to see some more discussion on this. My understanding is that less tire pressure=more grip.....possibly at the expense of more easily damaging a tire. Is this correct??? Also, what are the "suggested" front and rear pressures for an '89 turbo???

Thanks

The DareDevil

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by SidViscous:
<strong>Try running what I had. Completely wacky. You would notice that change.

Suspect you both would feel a difference going to the spec.

36 all around gives the fronts not enough bite, 30 all around gives the rear more float.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">So, 36 in the rear and 30 in the front? Sounds like a plan

Tremelune

Yeah, I want to hear more discussion on tire pressures in general, our cars in particular.

I've got cookies, 215/60/15

SidViscous

"less tire pressure=more grip.....possibly at the expense of more easily damaging a tire."

Abso-fecking-lutely. Less tire pressure does give you more grip, if your running 1/4 mile great, but on the road, when you take corners, you put more pressure and heat on the sidewalls. it also gives you more float (Less precise steering) Once when driving to Maine in the Duster I was wondering why the car was floating all over the road. Left rear was almost flat. Bad enough sidewall damage that I had to replace it before going home.

As to precise tire pressure. What exactly are you going to do. WHat kind of tires do you have. What is the average temprature. What altitude. Theres many variables.

I would start with the recomended and play around 5 psi here or there. Find a ratio that works for you. THen start playing around a couple of psi Here and there. Till you find something you like.

Less PSI more grip. More psi more precise and more MPG.

Amd yeah DD, in this car that's a good formula, but it won't work for all cars. Just because we have a higher weight differential in the rear. Try that in a muscle car and you'll wonder why your going backwards coming out of an off ramp.

Sami951

It really depends on the tire, too! Last summer I had 16" Pilot Sports on the ex-S; at first I was running ~2.6 bar on all corners (~39 psi) ... *way* too slippery rear. Left the fronts as they were, dropped the rear pressure to ~2.2 bar (~33 psi) and voilá, massive grip - suspension was stock springs/torsion bars, koni yellows in all corners and 968 M030 sways.

With that set-up, anything below 30 psi in the tires felt just wrong...

It's surprisingly easy to spot a change in the pressures if one drives the car daily. A few psi drop gives noticeable difference in how bumps etc. feel. Or maybe I am psychic

gilwong

Factory recommendations are 30 front/36 rear for normally aspirated 944 and 36 all around for 944 Turbo. I keep my tires between 34 and 36 at all times. If you want a soft ride, use 30 or 32. 34 or 36 will give you noticably harder ride but much sharper turn in response. Remember to measure pressure on cold tires. Do not run underinflated or overinflated tires as this ruins handling and causes uneven wear on tires.

Ciao.

pete944

The factory specifies different pressures in the front & rear to make the car more likely to understeer. I'm running 33psi all around and the car is more neutral and responsive.

jim968

With new Bilsteins & Michelin load range E's, 65 psi front, 80 rear ...oh, wait.. oops, that's for the Roadtrek!!! (it only weighs 3.5+ tons...8=)...)

seriously, this is a topic that will no doubt be argued to death, since all of will have slightly different ideas of perfection, differing operating conditions, and differing subjective judgements. That said, my '88 na was _perfect_ with 32 front and 36 rear. That's on mountain roads with lots of twisties, too. These were the pressures recommended by the '944 specialist' at the local P-car dealer the first time I took it in for service. The 968 seems happy with the same.

I'll also note that I got pretty even treadwear at those pressures.

Jim, "Some days you're the windshield, some days you're the bug."