Tyre Pressure

[harlowrog]

This may have been answered before but I couldn't find it. Should the tyre pressure be increased when fully loaded with people and luggage! No where in the manual or on the 'B' pillar is there any reference to increasing pressure from the normal 32psi (RX300SE 18in wheels). Every other car I have ever owned recommends an increase with 3+ people on board. My wife's Mondeo go from 31 to 45 on the rear for example. Any advice greatly appreciated as always.

Roger.

[dhs]

Just returned from a round trip to Spain, fully loaded both ways. I left the pressure at the standard setting as running at high speed for long distances increases the heat and therefore the air pressure.The car performed to the usual high standard with no extra tyre noise or excess heating of the tyres.

[Realspeed]

AS far as I am aware all quoted tyre pressures are for cold tyres. as regard runing pressure would I suspect depends if used on road or off road surfaces - the make of tyre- amount of wear -load/weight applied to the tyres-heat generated etc etc.

Therefore the quoted tyre pressure would in most cases allow for these differences.

If the tyre is obviously looking a bit deflated then get it checked out it may only be a sticking valve( soapy water on the valve would show up by bubbling if this was the case)

The manuals say tyres should be swapped at intervals but its not done on dealer services unless asked for.

On the mondeo it seems a bit extreme to have a difference of 14psi to say the least and I would suspect its a missprint, and I would check with local tyre fitting depot who have charts on different car makes and their type/pressure of tyres.

Over or under pressure in tyres show up on wear of the tread can't remember if worn in centre/ outside edge is over or under inflated but I'm sure if you lookup on a search engine about tyre wear would put you straight.

On a lighter note don't worry too much tyres only go flat at the bottom.

http://www.orbweb.net/autoshop247/tyre_tal...afety_tips.html

this addy may be of some help.

Realspeed

[harlowrog]

Thanks for the help, Made a slight error the Mondeo psi's, 41 not 45 when loaded, I have had many cars that have much higher pressure with 3+ people and luggage, it's always more on the rear than the front though as in the Mondeo's 31 all round, then with a load it's 35 front and as I said 41 rear. It seems the RX has the same pressure regardless of the load on board, just really wanted my mind put at rest that there wasn't an ommision in the manual.

Cheers, Roger.

[Cymro]

I'm gald this issue has been raised. Of all the cars I've owned, only the RX300's handbook implies that the tyre pressures do not need to be increased when the vehicle is fully loaded. The pressures (on my RX mark 1) are to be set at 33psi all around, irrespective of load. I too wondered whether that was an oversight: it's not as if the tyres are huge, or are set at a very high pressure.

But as no-one has come up with anything to the contrary, so be it.

Does anyone know whether the same is so for other 4x4s of about the same size e.g the Merc ML; Range Rover / Discovery; BMW etc? Or is this a lexus-only quirk ... in which case it warrants an explanation!