924Board.org

[Tardis]

Hello,

I have a 1979 Porsche 924, European. I have no manual at all. Could someone be so kind as to give me the correct tire pressure in bars for my 924 or point me to some available info on the Internet.

Thank you

[teo]

As far as I know it's 2.0 bars both front and rear for the 185/70R14 tyres, will check it at home later, and correct myself if not.

[Tardis]

Thanks a lot Teo

[Diesel]

29 PSI on this side of the pond.

[teo]

So I checked it, yes it's 2.0 bars for front and rear.

BTW, Tardis, welcome to the board, and have fun with the 924!
Check out http://www.924.org and then the links section for info on the car.

Here's a link to a french 924 club:
http://www.club924.fr.st/
but don't even think about leaving us!


Hey Diesel,
it would be interesting to build a Diesel 924, with a new TDI, and lot's of torque ,
or is it already done?

[Diesel]

That would be interesting alright. I'm starting to like the old Audi 2.0 though. Once you start working on it and knowing it's tricks, they aren't bad engines.

[kaffine krazed]

I've been looking for a diesel engine that I like and will fit. I know alot more about diesel engine performance than I do about gas engine performance. My brother drag races a Dodge 3500 quad cab 4x4 diesel it's my job to improve his times.

[Paul T.]

Gentlemen,

I do not care one little bit what the manual recommends for tire pressure, inflate your tires to the range that is printed on the sidewall of your particular tire. If you fail to do this, you risk the danger of running your tires hot and having them come apart on you at 70 or 80 mph. Those tires were designed for for a particular weight range and a particular air pressure range. If you choose to ignore this, then you are risking the chance of a blowout. The car manufacturer only recommends those lower pressures for a smoother or quieter ride, this was achieved during their testing of the car under very controlled conditions. If you wish to run you vehicles tires at these lower air pressures, then you need to order special tires that are rated for these kinds of conditions.

[Mark CSC]

Paul

Forgive me if I have got the wrong end of the stick but.....

The bar and psi that the manufacturer recomends are for THAT car. The rating on the tyre says what the maximum pressure that shouldn't be exceeded is. As long as you pick a tyre that has a higher maxium rating than the manufactures rating you will be OK.

Mark

[Rick MacLaren]

Mark: I hear what you're saying, but the stock tires on the 924 were, if I'm not mistaken, 185 14 85. What if I installed, sometime in say the last 20 years, another pair of tires with different specs?

Let's say I installed, very likely, a pair of 215 16 55's on my turbo? What then?

I think the tire is the safest place to find the correct tire pressure. But that point notwithstanding, you SHOULD probably have the rear tires with less pressure than the front tires.

Rick

[teo]

Hey guys,

What I said is from the Haynes manual, as that's the only thing I have for my car, and I stated that 2.0 bars are for the 185/70R14 (ok, an H is missing for the speed index, it should be 185/70 HR 14) standard tires. But here's the rest from Haynes:

(I hope this is not copyrighted material, as it should come with the cars, if so, contact me and I will stop publishing it , thanx)

1976-1979
Rims: 5 1/2 J x 14
Tires: 165 HR 14
Pressure, front and rear: 2.0 bar (29 psi)

Rims : 6 J x 14
Tires : 185/70 HR 14
Pressure, front and rear : 1.8 bar (26 psi)

1980-

NA

Rims : 6 J x 14
Tires : 185/70 HR 14
Pressure, front and rear : 2.0 bar (29 psi)

Rims : 6 J x 15
Tires : 205/60 HR 15
Pressure, front and rear : 2.0 bar (29 psi)

Turbo

Rims : 6 J x 15
Tires : 185/70 VR 15
Pressure,
front : 2.0 bar (29 psi)
rear : 2.5 bar (36 psi)

(5 bolt)
Rims : 6 J x 16
Tires : 205/55 VR 16
front : 2.0 bar (29 psi)
rear : 2.5 bar (36 psi)

Ooops, Rick, they have it the other way around, with more pressure at the rear...

Anyway, check the tire shape after inflated, you will see if it's >>too much<< over or underinflated.

And some more about tires:

( http://www.yokohamatire.com/04a1d.html , you can also find the link at the links section, tyre related)

Temperature Resistance
The UTQG also provides a measure of resistance to heat generation under normal operating conditions. The test is conducted under predetermined standards for inflation and loading. Excessive speed, underinflation, and overloading can all cause adverse heat build-up. Sustained high temperatures can reduce tire durability. Resistance grades are branded on the sidewall.

Resistance Grade A: The maximum performance level indicating the tire withstood a half-hour run at 115 mph without failing.

Resistance Grade B: The tire passed 100 mph but not 115 mph.

Resistance Grade C: The minimum performance level indicating that the tire failed to complete a half-hour at 100 mph

These are labelled as Temperature A, B or C, it's time to check your tire for this rating!

Sorry being so long, it looks like I have too much time.

Teo
'80 924 NA, in the shop since the beginning of the summer

[Paul T.]

Mark,

I understand what you are saying. However on the sidewall of every tire I have ever put on any vehicle I have owned, there is a psi range for that particular tire. Therefore, one can only understand that the range you see on the sidewall of the tire is what it is supposed to be inflated to. Classic case, the Ford Explorer and Firestone tires. The minimum tire pressure as recommended by the manufacturer (Firestone) for their Wilderness tires was 30 psi. However, Ford recommended in the Explorer manual that they be inflated to 26 psi. That was found to be where the tire was the quietest and smoothest during their testing on the vehicle. The tire was not designed for this tire pressure. Hence, the tire heated up and came apart. I also had my theory checked withe Mecedes-Benz house. My wife drives one, and I recently had new tires put on it. I called them to ask about the tire pressure, and they said put in what is recommeded by the tire manufacturer. That is my spin on the whole thing. I will always inflate my tires to what the tire is rated for, not what the vehicle manufacturer recommends.

[teo]

Paul,

it's dark, cold, raining, foggy, but I took a flashlight and checked the tires on my other-than-Porsche car (escorted by strange look from wife .
I only have a max. pressure rating, not a range. The writing on the wall of the tire says, check your owners manual.

I believe there is some close relationship between the pressure in the tire and the weight of the vehicle, max. pressure for this tire is 44 psi (3.0 bars), my owner manual says 1.9 bars (27.5 psi) for the front. Now, with 44 psi in the front I would use the pressure indicated as max. in the tire, but I'm sure with this setup I would be all over the road, with minimum grip, as only the center line would be in contact with the road and with a good spherical shape.

So, as long as I only have a maximum pressure stated on the tirewall, I will keep the car manufacturer settings + a little. (2.1-2.2 instead of 1.9, how could I inflate it at the gas station to 1.9 >>cold<< anyway?)

Teo

[Paul T.]

Teo,

I'm sorry you had to go out into the dark, cold rain. I didn't want anyone to have to do that. Anyhow, I have never seen "check your owners manual" on the sidewall of a tire. I guess there are some differences between the USA and Europe. Differences between tires that is. I've always seen a recommended tire pressure range on the tires I have bought. I guess the tire manufacturers have different things they put on the side of their tires in Europe as opposed to what our government makes them put on over here. Anyhow, I guess there are just different ways of doing things all over the world.

[teo]

Paul,

agreed, and that is what I was trying to get to, to make it clear to everyone, that before you use some info, better check it if it's true for you and fits your needs or not.

Teo

"
You are all individuals!
Yes, we are all individuals!
I'm not!
Ok, so you aren't!
"