Tyre pressure - speed/fully laden

[AP2000]

Just trying to work out the correct tyre pressure for my car, it was on ~27psi so I pumped them up to 32psi at the petrol station.

In the petrol filler cap, it shows 32psi all round for normal loads. But now I'm wondering if I should set it to fully laden/speed. I'm the only one that sits in the car most of the time, but I drive around 300 miles a week, mostly on dual carriageways and A road at 60mph+

Would the fully laden/speed pressure be more suited to me?

Car is a 2003 Toledo TDi 130.

Thanks

 

[Jonny]

I would say no, because the tyres would be over inflated resulting in them being worn on the middle section of tread. Also, being over inflated, you won't have the full contact area on the road surface which can be dangerous in the wet or under heavy braking.

Keep to the recommended pressures (for the conditions) would be best, i.e. normal for normal loads, fully laden for carrying a car full of passengers & luggage

 

[AP2000]

Thanks. I always found it strange how they quote the same pressure rating for a full loaded car and a car driven at constant high speed.

 

[Jonny]

Just wanted to add, I check my tyre pressures fortnightly at most, or before I go on a 'long' journey (100+ miles is long for me!) and keep them at 33psi.

A few weeks ago, I pulled into a services on the M5 and decided to check the front tyre pressures as the car felt a bit "squidgy" Anyway, with the heat generated over the previous 75 or so miles, the fronts had gone up to 39psi and the rears were 36psi.

So, if you're over inflated to start with... there's the small possibility of being over pressurised resulting in a blow out maybe

 

[cardaft]

Which goes to show that you should always check your tyres when they are cold, preferably in the morning before the suns got on it, as then one side will have more pressre than the other if ones sides in the sun and the other isnt.

The best thing to do it buy a little pressure gauge from halfords, i got on the other day for £5 and its superb.

 

[AP2000]

They are useful, I got one for a xmas present years ago and keep it in the car. Least then I know the tyres are cold outside my house when I check the pressure.

They are very accurate, and to one decimal point.

 

[TDI_luver]

Air pressure increases with temperature when the container volume remains the same, (p=V*T, Charles' Law, basic physics) so checking the pressure when the tyres are hot is meaningless. Only check cold pressures for meaningful reads.
Higher tyre pressures are recommended for mtootrway driving / heavy loads because the tyres flex less when pumped hard, therefore they will heat up less, therefore the rubber is less likely to overheat in the walls and blowout.