4psi rule
Submitted: Saturday, Jun 26, 2004 at 09:52
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Member - Eric K (NSW)
Can anyone tell me what the 4 psi rule is for tyres if you have say a difference 7psi from cold to hot does that mean that your original psi was to low or to high.
Reply By: Hedonist - Saturday, Jun 26, 2004 at 12:47
Saturday, Jun 26, 2004 at 12:47
To add to the succint explanation above:
The change in pressure is an indication of the amount of heat generated by the tyre as the carcass flexes under load.
If a tyre is underinflated the flexing of the sidewall will be excessive and the tyre will generate a lot of heat which will cause a larger increase in pressure that would occur if it was correctly inflated to start with.
Conversly, if the tyre is overinflated, there will be very little flexing of the tyre carcass and a correspondingly smaller increase in the inflation pressure...
Cheers,
Pete
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Reply By: Topend - Saturday, Jun 26, 2004 at 12:47
Saturday, Jun 26, 2004 at 12:47
Tyre pressure should be checked when cold, although sometimes this is not possible. Try your high and low pressures when cold then go for a decent drive. Then recheck them and see what they read when hot. Remember your hot pressures for those times when you have to alter the them while hot.
As for the 4psi rule, I sometimes vary my pressure by more than this depending on weight etc.
Topend
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