Psi - Do you under or over inflate?

[berg]

Hi guys,

have read many topics via the search function on this as am experimenting with psi for optimum handling (not bothered about tyre wear unless it was drastic)

At present am running 36F and 34R (cold) on my ED30.

This seems to run well and I see many people have run less than the recommended pressure on the fuel cap for better results.

What confuses me is the comments from TT (Teutonic Tamer, who seems to be an outspoken yet very well respected member of the forum) as he said he was running 42F and 37R.

Has anyone else ran these pressures? Over 40psi on the ftone seems very high and what potential gains could this give?

[E30Dom]

I run 38psi all round as Vw says to do... You'll notice wear on edges of tyre if underflated, and more wear on central section if over inflated, this is normally a better indicator... On a track you would possibly play with psi and set colder as tyres heat up and expand, bet on road it's pointless IMO...

[the bruce]

I run 38psi all round as Vw says to do...

Not the worst recommendation.  

You'll notice wear on edges of tyre if underflated, and more wear on central section if over inflated, this is normally a better indicator...

No, modern ''ZR''- oder ''Y''-rated tyres have stiff tread section, so over inflated tyres
won't generally show visibly more center wear. They commenly provide less grip though.

[Big Red T]

I find 35/36 psi all round works lovely. Tyres must be checked cold as pressure raises when warm even in general driving. 35psi when cold probably becomes close to 40 easy when hot. I've checked my 35psi before and when hot general driving have seen 38 easy.

[FamilyDub]

I find 35/36 psi all round works lovely

+1....  35/36psi is what I use...

[Nodz]

A1 put 38 in mine when I had the new wheels and tyres put on and it was great, got it back from the stealers the other week and they dropped them to 34 and it don't feel as good so put them back to 38

[berg]

think will put up to 36 psi at the back and see how is

[56OctyVRS]

38psi seems a bit high for a road car.  Even high powered evos have only 30 psi on the front from factory.  I have an Octy vrs and put 33 psi all round and find that is a good balance between handling and grip.  At 38psi cold (circa 44-45 warm)  you will be mainly driving on the centre section and running close to the tyres pressure limit. Higher tyre pressures do give a more positive steering response but at a cost to grip, as the tyre pressure increases it curves outward so you actually drive on less tyre, which cant be good!  
To put it into perspective an F1 car from cold has pressures of about 1.1bar and as they use nitrogen gas so they dont increase much more in pressure. Most road tyres have strengthened walls so you can use less pressure without them deforming under load. You dont need high tyre pressures to have good handling.    

[robdf2]

i only put 30 psi in my cupra 

[berg]

i only put 30 psi in my cupra 

and presumably you find it handles very well?

[Kiwi]

There are a few factors, and one has to be Tyre brand ?

[Carrera2RS]

I have spent a lot of time adjusting settings on a Pirelli with bilstien pss10, walk, TT arms, nested roll bars and I have settles on 35F, 33R

I would simply experiment, don't forget manufacturers are stuck with dealing with 4 up and high speed under inflation issues that for most will never exist, plus the tyre will be increase in the real world in those circumstances.

Drive on a winter holiday at speed with the car rammed, you should increase tyre pressures.

[no golf clubs at all]

36 all round 

[jamma]

What is the recommened PSI on a Standard GTI?

Incidentally I ran 44 PSI on my old 911 rears as recommended by Porsche, now thats hard 

[Jogon]

32 all round for me...