Tyre Pressures

[Phil Mcavity]

hmmm does seem abit high 42psi, i would follow the owners handbook tbh, only higher pressure for heavy loads or possibly the in-laws

[rdfcpete]

I have the 17" Monza's. The Hanyes manual reckons 28psi all round, which I think is way to low.

I was thinking 32psi all round to keep the highest possible MPG?

[Gene Hunt]

Ever had any problems with the T.P.S ?.

[icenutter]

It doesn't actually measure the pressure, rather it compares the rotational speed of the tyres using the ABS sensors to work out which one is spinning faster, which is probably then flat.

The actual pressure the tyres are at doesn't have that much to do with it.

[Teutonic_Tamer]

The reason for my query is that T_T has said on the other forum that:

I run mine at 42 front and 37 rear.

And in my RS4 I run 48 front and 45 rear . . . .

He said that this will provide good handing capabilities. I've never pumped a tyre into the 40's, so it just seems like a lot to me!

Is that some kind of 'mental wall'.  I've pumped many a tyre to 120 psi - OK, not on a road car tyre, but still on a road legal 'normal' vehicle!  Best you check your pram wheel space saver, because that needs specifically pumping up to 61 psi!!

Not that I'm questioning his judgement, but I was just asking to see if anyone else adopted a similar approach.

I have no interest in setting them for ride comfort or mpg, but merely for handling capabilities!

As I have often stated, the tyre pressures on the fuel flap or B pillar are simply RECOMMENDED pressures - which must be suitable not to rattle your grannies dentures out, whilst still maintaining some kind of decorum in the twisties.  The owner/driver is perfectly free to 'tweak' their own tyre pressures to suit their own preferences.  Finally, those manufacturer recommended pressures are ONLY for OEM spec tyres, with OEM tyre sizes and OEM load indexes - so even if you keep an identical tyre size and load index as OEM, but change to a non-OEM tyre such as Mich PS2, Eagle F1, Toyo Proxies, or whatever, you then need to re-apraise what tyre pressures work the best for you.  So for all those 'wheel whores' out there (not mentioning anyone, except <cough> Hurdy and Greenouse <cough>  ) - you got no chance!  

[Teutonic_Tamer]

32 all round on My Mich's pliot exhilto's


Toast

That must handle like a Chivers jelly! 

[Mark_GTIV]

So then the question...

People with BBS CH 18x8 s.. If you are running Michelin Pilot Sport 2 in 225x40 18.. what pressures do you find work best for 'spirited' driving?

[Teutonic_Tamer]

Do remember that over or under inflation will lead to uneven tyre wear.

Not really the case with decent steel-belted radial ply tyres.  You can have them grossly over or under inflated, and they dont really affect the even-ness of the wear.  The most common cause of uneven wear is power steering - yup, power steering - watch the amount of peeps who now merrily twizzle their steering wheel from lock to lock on a completely stationary vehicle - you would never have done that in pre-power steering cars! - this wears both outer shoulders excessively on front tyres, and can be countered by increasing the tyre pressure in the fronts anywhere between 10-15 psi.  The next most common, again mainly affecting the fronts, is too hard cornering, particularly on low speed corners such as roundabouts - this wears the outer shoulder, and again, adding 10-15 psi will cure this.  Finally, poor wheel alignment, poor wheel balance, and worn dampers can all cause uneven wear - again, all considerably greater than simple over or under inflation.

[Teutonic_Tamer]

^ Thats a good point actually, had forgotten about that! 

And you can again forget about it, because unless you are running 'race tyres' with soft carcasses, you don't need to worry. 

[Teutonic_Tamer]

i run mine at about 33 at the front and 31 on the back, dont ask me why, ive not got a clue! ive just done it for years with 18s

You must like it slightly more 'comfortable' then. 

[Teutonic_Tamer]

As per the recommended handbook pressures, I have mine set at 35 PSI all round. Don't forget to check them when the tyres is cold!

Best advice of the thread so far!   

[Teutonic_Tamer]

34psi all round for me, might try 36psi to see how it feels

I honestly doubt you will even be able to tell the slightest difference with just a 2 psi change.  Try upping just the fronts by 6 psi, and see how you get on. 

[Teutonic_Tamer]

Im running 2.4 front and 2.5 rear.  Once up and running this rises to about 2.5 front and 2.6 rear and its very difficult to tell any difference.  What does make a difference is the temp, in this weather the tyres are running at about -1 / -3 in the mornings and only getting upto about 18 / 19 c  In the summer this gets upto about 29 and the difference is BIG.  My advise it to get the tyres up to temp before using the full handling capabilities 

That too is crucial advice.    If you start chucking a car around hard on cold tyres, you can actually tear the tread rubber.

[Teutonic_Tamer]

I have the 17" Monza's. The Hanyes manual reckons 28psi all round, which I think is way to low.

Erm, the Haynes manual, more commonly reffered to as the HBOL - or "Haynes Book Of Lies", does NOT list the car manufacturers recommended pressures, so should be completely ignored!

What does the sticker on your fuel flap say?  If it lists them in bar, then bung them into an online conversion site to convert them into psi

I was thinking 32psi all round to keep the highest possible MPG?

32psi is still too low for optimum mpg on a relatively heavy car like a Mk5 GTI (or any Mk5 Golf, especially the lard-barge of an R32 - dons nomex underwear!    )

[Teutonic_Tamer]

hmmm does seem abit high 42psi, i would follow the owners handbook tbh, only higher pressure for heavy loads or possibly the in-laws

But it all depends on how you drive.  If you drive generally fairly sedately - and by that I simply mean no hard cornering, no trying to outbrake Lewis Hamilton at every roundabout and junction, etc - then for standard loads, the standard pressures will be just fine.

But if you are wishing to maximise grip from the tyres whilst exploring the maximum potential from the handling, and using your 4pot Alcons/APs/Brembos to the max, then you really do need to consider tweaking them.