Tyre pressure: never guessed!

[Oliver]

Never guessed how a subtle change in tyre pressure could make such a big difference in handling!
I increased rear tyre pressure up to 2.8 bar (which is on the high side, I know) and kept the front at 2.6.
Result! Understeer has virtually disappeared, the car's perfectly neutral in any of the situations I've thrown at it! 8)
Tomorrow I'm going to try and depressurise all the wheels by .2-.3 bar to increase traction...
Any thoughts on ideal tyre pressures front/back?

[Johann F]

2.8 bar is dangerously high for a tyre - about 42 PSI!!!. Try 32/36. If you remove your front ARB you can run equal pressures and have neutral steering.

[Jezzadee]

That LPG kit must weigh a bit though - I can't recall offhand the recommendations for rear tyre pressure when fully laden, but it was surprisingly high. I currently run 32psi front, 34 rear, but the front seems a little soft. Owners manual I believe says 30 front, 32 rear, but that's way too soft.

[Johann F]

In my 91 handbook it gives 2.7bar as the maximum for the rear at maximum load and above 100mph. If you are not loaded up you are loosing a lot of grip with high tyre pressures. The answer is stiffer side walls from lower profile tyres on bigger rims or just uprated tyres in the V rating (or both)

[Matthew]

Maximum tyre pressure is embossed on the sidewall. Make sure the current pressure isn't in excess of this.

You'd be surprised how high tyre pressures get during a long motorway cruise

[Oliver]

Nah the tyres said 3 bar max.
And even now when looking at the car it's like the tyres are way too soft. :-?
Oh and I took a look at removing the front ARB for improved handling... I havn't got one.
As I said, tomorrow I'll lower all of the wheels by .3 bar, which should give 2.3 front and 2.5 rear.
Oh for you imperial lot that's 34-ish front and 37.5 rear.
We'll see how it goes then.
Cheers

[Johann F]

If you haven't got a front ARB to remove you are 1/2 way there - it's very easy to add a rear ARB to do get the same result.

[Alex]

Originally Posted by Oliver

And even now when looking at the car it's like the tyres are way too soft. :-?

Different makes of tyres have considerably different sidewall stiffnesses. Bridgestones typically have stiff sidewalls, the Falkens I used in the past were way too soft to be used on a Saab, and the Goodyear Eagles are roughly midway between the two.

[Oliver]

They're Firestone's.