Tyre pressure

[charliechalk]

Well, it's not written on the outside wall, so i'm guessing it's on the inside wall but thanks for the help guys

[kingmick]

" low profile tyres i have always used slighty less pressure, there side walls are much stiffer" there is the problem, i can not read and missed the "there" before side wall could have sworn there was a "makes" before the "there"!hahahahahahahahaah

[TRAV-KE55]

Hahaha, like i said earlier mick, we are arguing the same thing!!lol
Normally i would think your a tosser and not reply but i looked at your rep and thought he must know something i dont!!!
Trav

[kingmick]

lol what a pissa! Meaning me miss reading it and trying to explain How lower pressure dosnt make the side wall stiffer! hahahaha

[Rodger]

After all that I'll put up an example of what I do for tyre pressures on my Family 2002 Camry and my Landcruiser.

The Camry has 17x7 with 215x45 tyres.

Fronts I run at 40psi cold and I drive it hard enough when on my own to knock the corners of the tread.

Rears I run at 36psi cold.

The difference takes out a bit of understeer.

I also watch the tyre wear across the tread. If the centre is wearing more than the outside I'll drop the pressures down 2-4psi.

This is how I esentially set the pressures on my Landcruiser.
A Heavy front and positive camber means I tend to run higher pressure to get more of the centre of the tread on the road. The rear is lighter and too high a pressure was wearing out the centres so I drop the pressure down to get the outside of the tyres on the road. Then I change it all when I tow.

Sometimes if a car is running low profile tyres (55 or lower say) and is lowered with stiffer springs then taking out a couple of PSI (say from 38 down to 36) can mean it absorbs those annoying cats eyes and concrete road joints.

Regards

Rodger

[Stefan]

...shouldn't you be measureing tyre pressure hot ?

[MR22ZZ]

doesn't higher pressure on the front create more understeer?

and yes the pressure should be measured cold... as it's more consistant. If you could tell me what temperature 'hot' was, then you would have an arguement to your case, but in most cases 'cold' means 18-25 degrees more often then not.

[Stefan]

I see what you're saying, but when people say "32psi", do they mean @hot or @cold?

Maybe it's 18 in the middle of the day in winter in NSW, but it isn't in Canberra or Hobart

[YLD-16L]

but when people say "32psi", do they mean @hot or @cold?

For passenger vehicles the reference is always made to cold tyres.

[Rodger]

It's just easier to do cold and I just adjust on what I see and feel.

Strange how tyre pressures work with regards to understeer and oversteer.
This can be seen in some of the formula/spec race series where tyre pressures are all that can be changed and the guys that know the art just simply run faster. An adjustment of 0.25psi can mean a lot in say an Indy Car.

Someone reading this thread will point us in the right direction or spill the secrets, I hope, as I have not read an exact definition anywhere that nails the reasons and sometimes I struggle to understand.

Suffice to say as I beleive it and I am no expert.
It has something to do with changes in tyre sidewall flex, the resulting change of contact patch on the road, the change in direction of the load on the tyre from changes in body roll and a few other things.

Regards

Rodger

[TA-022]

38psi everyday all day. 13" 205's so flex is huge!

higher pressure reduces tram lining (cause 7" wide front and back is a bi@tch) but trade offs are a harsher ride and im prob running out the centre of the tyre from a slight over inflate.


thems the brakes but! lol