Tyre Pressure Hot/Cold??

Senna · 29-12-2007 05:54AM #1

just pumped up all 4 tyres (when they were cold), then went for a long drive and checked the pressures again, they had gone from 30psi to 36psi.
Let some air out and brought them to 30/32psi again (tyres still warm) and i felt the car drove a lot better and more stable on twisty roads.
So my question is, should you pump your tyres up to the recommended psi when they are hot or cold? (i always though cold)

Edit; i used a proper pressure gauge, not a forecourt one.

Wishbone Ash · 29-12-2007 09:43AM

Senna wrote: »

should you pump your tyres up to the recommended psi when they are hot or cold? (i always though cold)

Cold.

peasant · 29-12-2007 12:09PM

theoretically you should fill your tyres at a defined outside temperature (I think it's 20 degrees) and an exact outside athmospheric pressure (dunno which one)

Failing that, cold will do just fine

Esel · 29-12-2007 03:02PM

Senna wrote: »

Let some air out and brought them to 30/32psi again (tyres still warm)

Don't do this!

Senna · 29-12-2007 04:47PM

esel wrote: »

Don't do this!

why?

Esel · 29-12-2007 05:39PM

Recommended pressures are for cold tyres. Pressure will increase when tyres warm up, and drop when they cool again. By reducing the pressure when the tyre is warm, you will have underinflated tyres when they cool.

Tyre Pressure Hot/Cold??

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