What is the correct tyre pressure for the full size spare tyre while it's in the boot? The tyre is 205/55R16 in steel rim.

 

Is it the same as what's written on the fuel cap, despite no weight of car on the tyre?

 

Also, is it right that I'll always have to remove everything and the tyre just to check the spare tyre pressure?

 you're not going to want to start adjusting pressures when you're stuck on an m'way hard shoulder with cars blasting past at 70mph+ ? Even if you carried a compressor...

 

Change the wheel pronto and gtf out of there!

I always have my Spare a couple of PSI more than the highest pressure set in the other 4 wheels.

 

Spares can sit in the boot for a few years and after time air weeps out.

 

I check the spare is hard every couple of weeks and check the pressure around 6/8 weeks.  

 

Nothing worse than a flat spare   

Does weight of the car change tyre pressure reading?

 

My brain thinks as you put weight on a tyre, it will increase the pressure ...... so that means the spare should be a few PSI less than what's written on the fuel cap, because there is no load on the tyre. But you are saying the opposite?

Hi WYX, use the same pressure with the tyre loaded or unloaded. I always keep my spare (full size) at the pressure of the highest setting I am using in the rears - second Mr Goldfingers suggestion if you're not in the habit of checking the pressure in the spare on a regular basis. Much quicker to lose a few millibars / PSI than to put em back in. 

@wyx087 - Believe it or not, "weight on wheels" doesn't affect pressure in tyre, because the volume inside the tyre remains constant.

Simply Clever with Spare tyre pressures,  Have them st the Max Pressure for that tyre when in the spare tyre well.

 

If you need to put on the car in an emergency then letting the pressure down is easier than having to inflate a tyre.

You obviously have a good tyre pressure gauge in the car anyway for checking pressures regularly to help reduce the need to use the spare.

Thanks all. Going to pump up the spare to quite a few PSI higher than fuel cap specified, it all makes sense now.

4 hours ago, wyx087 said:

Thanks all. Going to pump up the spare to quite a few PSI higher than fuel cap specified, it all makes sense now.

Hi WYX, 0.2 bar above the highest pressure you are likely to use fully loaded, high speed will be perfect.

 

4 hours ago, wyx087 said:

Thanks all. Going to pump up the spare to quite a few PSI higher than fuel cap specified, it all makes sense now.

 

4 hours ago, wyx087 said:

Thanks all. Going to pump up the spare to quite a few PSI higher than fuel cap specified, it all makes sense now.

 

On 11 June 2017 at 10:52, Awayoffski said:

Simply Clever with Spare tyre pressures,  Have them st the Max Pressure for that tyre when in the spare tyre well.

 

If you need to put on the car in an emergency then letting the pressure down is easier than having to inflate a tyre.

You obviously have a good tyre pressure gauge in the car anyway for checking pressures regularly to help reduce the need to use the spare.

 

+1

 

Hard as you can, so there's a chance of some air still being in it when you - or someone else - wants to use.

 

I once loaned out my previous Superb spare to an A3 driver for a few days.

 

Be honest, you just know you won't check the spare pressure as often as you think you will.

These upside down wheels are a pest that way.

But better than the wheels that used to live outside in a dirty cradle (I met one recently when helping a tourist with a flat and the flat tyre would not fit on the cradle where the narrower spare lived and had to be squeezed in the boot)