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Author: Subject: Tyre pressure formula?
RazMan

posted on 10/4/07 at 05:17 PM Reply With Quote
Tyre pressure formula?

Just trying to find the ideal tyre pressures for my middy - is there a formula for calculating them or is it just trial & error?

For example it weighs 800kg with a 60/40 split (60% to rear) and I'm on tyres - front – 205/40/ZR17 - Rear – 245/35/ZR17

Any help would be appreciated





Cheers,
Raz

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tks

posted on 10/4/07 at 06:29 PM Reply With Quote
a lower tyre pressure gives more grip because the tyre is less Round/more flat
sow the touching surface is bigger.

the ideal tyre pressure is that one listed on the tyre (tyre wise) grip wise i think its trial and error..

Tks





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snapper

posted on 10/4/07 at 06:51 PM Reply With Quote
Tyred temperature guage, if the temps are even across the tyre then the tyre is as square as it can be.





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RazMan

posted on 10/4/07 at 09:26 PM Reply With Quote
Every tyre has a maximum inflation pressure stamped on the side somewhere. This is the maximum pressure the tyre can safely achieve under load. It is not the pressure you should inflate them to.
- how can it be when the loading weight could be anything between 100kg and 500kg?

I have used an IR thermometer and get roughly even temps right accross the tread so I can't be far out at 20psi all round. I would be interested how others have arrived at their ideal pressures though.

[Edited on 10-4-07 by RazMan]





Cheers,
Raz

When thinking outside the box doesn't work any more, it's time to build a new box

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tks

posted on 10/4/07 at 09:28 PM Reply With Quote
The pressure stated on a trye of approx 2 bars is the best working pressure for suchs tyre! if the load increases to compensate its adviceable to add a bit of air to the tyre.

Tks





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Bob C

posted on 10/4/07 at 09:29 PM Reply With Quote
The tyre is an important part of the suspension of the car, and the pressure should be lower on a lighter car. I don't buy tks theory about grip - but am sure the opposite is true on a wet surface!!!
A lot of the 'bling' 7's have low profile tyres AND rock hard suspension - the low profile tyres will have high pressure to protect the rims - the ride must be awful!!!!
cheers
Bob

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RazMan

posted on 10/4/07 at 09:41 PM Reply With Quote
I agree Bob - if the loading increases then the pressure must also. Therefore if my 1.5 ton tintop and my 800kg middy both use the same size tyre, the tin top must run higher pressures to achieve the correct footprint.





Cheers,
Raz

When thinking outside the box doesn't work any more, it's time to build a new box

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