Edwill

Hi!

I've got 255/40/17 tyres on the back and 205/50/17 on the front. I currently pump them to 2.3 bar.

What is the correct pressure?

MikeN

The '93-'95 GTS was the only 928 factory fitted with 17" wheels. I believe the pressure for both front and rear for this setup was 2.5 bar, or 36psi.

JohanvdWalt

As far as I know you should always inflate lower profile tyres more than standard tyres as there is less tyre between the road and the wheel so its more likely to get damaged.
The opposite should be true for wider tyres as the pressure per square cm is less as there is more rubber to carry the weight.

That said I would stick to at least the original pressures.

Johan

Gretch

36 and 44 baby.............works for me. As you can imagine, this is a much debated topic.

MikeN

Gretch -

Are you talking about 16" rims or 17's? The 16's are 36/44 (works for me also), but for the GTS the rear 255/40 17" was dropped to 36 psi by Porsche, not 100% certain though......but know it was lower then 44.

heinrich

44 is just not realistic with today's rubber. Agreed much debated, but when you realise that 44psi is ***many tyres' max permissible pressure*** you realise that you just cannot safely do that.

Personally I go for 34 all-round. On 17's and 16's. Johan, wheel damage isn't the point brutha :-)

MikeN

Yes, valid point.......however I have found that different tires respond in different ways to the 44 psi mark.

The old Bridgestone RE71s (stock factory tire for the 928 GT) that I had on my previous '89 S4 5 speed were not good at 44 psi........funny as it was a factory tire. The middle of the tire would wear faster.......not that much, but some, and the ride/handling was not as good as when the pressure was set lower.

Now the Pilot Sports I have on the GT right now are perfectly fine with the 44 mark.......good ride and handling......and seem to wear much better straight across.

So some tires might be fine with it, while others may not.......

JohanvdWalt

If you live in SA it is my mate.

Johan

JohanvdWalt

I have to agree our highways are gr8 especially since installing the lazar scrambler.

In town is a different story though especially in the rain season. They do fix the potholes but once through is enough to cause damage.

Johan

Pierre Martins

IMHO the only good highway left in SA is PTA / Krugersdorp. You can still plant your right foot and go full taps for 15 to 20 minutes on a good day. Today was a good day for example, I made the 540i work overtime...

Nice to see more "Saffies" here. You guys gonna be at time trials / DK challenge this year? I'll be testing my 928 racer at Midvaal next weekend btw...

Pierre.

pgs928

Pierre

I have to agree the R28 is probably the best stretch of motorway in the Gauteng area.

Managed to get my S4 up to 27????km/h not so long ago

Peter

JohanvdWalt

Hi Pierre and Peter mail me at johan@wico.co.za

I'm trying to get the 928's in the Pretoria area together.

Johan

Edwill

And South Africa invades Rennlist!

I think I'll make the rears 2.5 and the fronts 2.3 then...

I recently (about a month ago) had my tyres swapped around (inside wear) and also rebalanced the wheels. Trusting the tyre company, I did not check the tyre pressure until this weekend when I filled up my tank. Much to my dismay, I realized that the wheels were on different pressures (one of the rears at 1.8 bar!!! ).

In this month period, I have travelled to Lichtenburg (via the R28 over REALLY bumpy roads) and other not so good roads. I didn't really hit any potholes, so can my wheels be damaged? How can I make sure? I certainly don't hope so, as I've got Boxster S mags and they cost R21 000 at Porsche!

Old & New

With wear on the inside you should have the alignment checked, your toe-in is probably set wrong.

Edwill

Thanks Old & New (Testament is it? )

I had them aligned two weeks before the swapping around, but the wear was from the misaligned period before then...