Tyre Pressures

[Hammer2001]

Was preparing the car for a family holiday to Cornwall next week, and was pumping up the tyres to the fully laden pressures, as we'll have five passengers and a full boot of luggage.
I was then wondering what to do once we've arrived and touring around, as then the boot will be empty and at times we might be back to under 3 passengers at times.

I looked in the owners manual and saw this:


"We recommend adhering to the tyre pressure for maximum load. However if you prefer an extra smooth ride and the vehicle is not fully loaded, you can select the tyre pressure for a normal load(no more than three people travelling in the vehicle) Should you wish to drive with a full load, you must increase the tyre pressure to the specified maximum"

To me that implies it is recommended to leave the tyres at the fully laden pressures all the time. I was thinking it would mean the tyres would be overinflated if I did that and it was just me in the car as I mostly the norm.

Driving around today after pumping up the tyres I felt the ride felt a bit better, so I am inclined to leave the pressure high all the time. Usually I use the normal load pressures.

What are your thoughts on this and what pressures do others use?

For the record the recommended pressures on the label on my car (255/40/R19):

Normal load
Front:32psi, Rear:30 psi

Fully loaded
Front:35psi, Rear:38psi

[zollaf]

stick to the higher pressures. not only will you get a better ride but better mpg as well due to less rolling resistance due to less sidewall deflection which also reduces heat build up. i run my 80 at the higher recommended pressures all the time.
out and out grip may be reduced though as the tyre is unable to deflect as much, so take it easy in the wet and on bends, and reduce the pressures if going on a track day

[robbyg]

My previous 2 volvos used to recommend higher pressure for economy. I followed their advice in my first one, i had to change they tyres early due to being worn out in the centre due to over inflation. suspect running at max all the time may save fuel, but might not actually save much money. Also it made the ride hard in the volvo, it was about 32/33 norm, 35/45 high so the range was larger than the A6.

If you arent planning on sitting at 100mph+ on the motorway all day i would compromise and go for 34 front and 36-37 rear for your holiday ie 70-80% values.

On another note, running the tyres at minimum all the time is not clever either, let say you check the pressure every 4-6 months and they lose a few pounds, in reality they are below minimum most of the time so wasting fuel.

Not sure what value i have added here now. I'll just shut up.

[fernar]

You could alway reduce the tyre pressure once you unloaded the car and then top it up at a petrol station for the return trip - if you cant get access to a place to pump up your tyres, just buy a small cheap electric pump - I got one a shell petrol station for £5.

I would suggest keeping the tyres at the correct pressure to reduce wear on the tyres - too much pressure and they wear out on the centres, too little wears on the edges - and of course breaking and fuel consumption are also effected.

Mind you if you dont plan on doing too many mile then the extra wear you will get at the higher pressure will be minimal - but your breaking will be a little less effective so take it easy with higher tyre pressure and no car load

[daycartes]

I always check and adjust tyre pressures at home since I found out that even the short ride to the garage increased the psi about 5. I realised that I had been running on over inflated tyres for years.

I have now covered 5,000 miles in my car. I checked and set the tyre pressures just after I bought it and checked them again yesterday and they hadn't changed one bit. I was quite surprised at this as the recommended interval between checking is IIRC fortnightly and I would have expected some deflation.

[skibuddy]

How much variance in the tyre pressure would you expect before the tyre pressure sensor kicks in and alerts you?

[johnsimcox]

How much variance in the tyre pressure would you expect before the tyre pressure sensor kicks in and alerts you?

It is at least 10% and should not be relied upon as an alert for day-to-day topping up. Its primary function is to alert you to a significant loss of pressure. Remember this system is based on using the ABS sensor to calculate relative rolling radii for each wheel. It is not like the system used on the C6 and by some other manufacturers which had a built in pressure sensor which is much more expensive and is often criticised for ongoing costs including the need to have the tyre taken off and refitted should the sensor fail or need a replacement battery.