Tyre pressure question...(not the normal one)

[Pep]

When manufacturers state the tyre pressures should they be set without any weight on the car? i,e. the car jacked up on that corner whilst the air is put in?

Surely correcting the pressure with the weight on the car will give an innacurate reading?

 

[JamesS]

You can set your tyre pressures either with the wheels off the car, the car jacked up in the air, or with the wheels fitted normally to the car and they will all be the same.

Having the car's weight on the wheels does not affect the pressures inside the tyres.

 

[kully]

what he said as you can only measure the pressure of the tyre from whats inside it .

 

[Pep]

ok cool, thanks for the replies.
I just wondered because at standard pressure my fronts still look low on pressure...

 

[kully]

ok cool, thanks for the replies.
I just wondered because at standard pressure my fronts still look low on pressure...

when you pump them up at the garage it tells you how much is inside , but i know visibly sometimes they look down

 

[JamesS]

Two questions for you:
1. What gauge are you using to meausure the pressures?
Don't rely on the gauge on your foot pump, or petrol station air line. Go down to Halfords or Machine Mart and get a reasonable pressure gauge (something like £5).
2. When did you set your tyre pressures?
Don't forget that with the recent drop in ambient air temperatures, if you set the tyre pressures a few weeks ago your tyre pressures may well now be 2psi lower because of the drop in temperature. Also, remember to set the pressures when the car has been stationary for a long time (so the wheels aren't warm) and also when the ambient air temperature is quite cool.

 

[Pep]

James, my dads got a decent compressor that I am relying on for the pressures, although I could treat myself to a proper gauge?

Also, I check all of the tyres every 1/2 weeks everytime i clean my car just to be on the safeside, like you say the lower temperatures have affected the tyres but i've topped them up accordingly.

 

[JamesS]

Doesn't have to be an expensive gauge. I've got one of these http://www.machinemart.co.uk/shop/product/details/ilpg1-tyre-pressure-gauge-with-in-line-h (by the looks of it you may struggle to get this from machine mart now) and its readings are virtually identical to the £300 pressure gauge we have at work.

It's a useful thing to have in the car just in case you ever think the tyres look soft and you want to check them.