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I just wondered what pressure you LS430 owners have.  I've always done 36psi all round but as I'm driving to Austria next weekend I wondered if I'm over inflating.

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If you don’t have an owners manual...do get one as it’ll be useful.

Depends upon speed and load but you won’t go too far wrong around 30 but please check exactly as it makes for safe, efficient driving.

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Handbook is quite specific, depending upon tyre size and loading. Normal is 35 all round. I am now on hols and loaded up, so front 35, rear 41. I have noticed incorrect tyre pressure have a real impact on handling, of course as well as being dangerous.

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I found 36 psi worked best for me. 

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57 minutes ago, Tinonline said:

If you don’t have an owners manual...do get one as it’ll be useful.

Depends upon speed and load but you won’t go too far wrong around 30 but please check exactly as it makes for safe, efficient driving.

Thanks for the replies, I do have a manual but it's Japanese so not much use. I do seem to remember from my previous one that 36psi was the norm but I thought I'd see what others were doing.  We won't be loaded, apart from the last leg from Calais where the boot will be full of wine!  I won't be driving too fast but I will try it flat out in Germany for a short burst, just to see if it's still limited from its life in Japan.

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I am rather surprised at the figures quoted here. The placard on my door pillar gives 33psi all round except with five passengers plus luggage in which case the rears to be 39psi. This for speeds below 210 kph. Do any of us exceed that speed?

Mine is a facelift 2004.

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15 minutes ago, GrahamG said:

Do any of us exceed that speed?

of course  :biggrin:

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21 minutes ago, GrahamG said:

I am rather surprised at the figures quoted here. The placard on my door pillar gives 33psi all round except with five passengers plus luggage in which case the rears to be 39psi. This for speeds below 210 kph. Do any of us exceed that speed?

Mine is a facelift 2004.

Are you on 17" wheels or 18?

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I have 18" wheels. Does that account for the difference?

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Mine has 18" wheels and I run 33psi. I tried 36 on our trip to France last year and it made the ride a bit harsher. 

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2 hours ago, GrahamG said:

I have 18" wheels. Does that account for the difference?

I don't know but mine has 17" wheels, maybe because it's an import, who knows! 

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27 minutes ago, BigBoomer said:

Mine has 18" wheels and I run 33psi. I tried 36 on our trip to France last year and it made the ride a bit harsher. 

That's what I'm concerned about.  I want the drive to Austria to be as smooth as possible.  

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Bit late in the day, but could you not have tried it at 36psi, let them cool, try again at 33 and then maybe 30? If I had half a day or day spare then I'd have tried that.

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21 minutes ago, genius149 said:

Bit late in the day, but could you not have tried it at 36psi, let them cool, try again at 33 and then maybe 30? If I had half a day or day spare then I'd have tried that.

I've got all next week spare so I'm going to try it at 33 and 36 just to see if I can feel the difference.

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Mine runs on 17 inch wheels so probably accounts for the difference. I follow the instructions in the manual . When I lost  pressure because of leaking alloy wheels the handling was noticeably awful, more than in any other car I have driven in similar circumstances over the years. I do think it is important to follow the tyre or car manufacturers guide, as there could be legal and insurance consequences.

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38 minutes ago, RgrWynne said:

Mine runs on 17 inch wheels so probably accounts for the difference. I follow the instructions in the manual . When I lost  pressure because of leaking alloy wheels the handling was noticeably awful, more than in any other car I have driven in similar circumstances over the years. I do think it is important to follow the tyre or car manufacturers guide, as there could be legal and insurance consequences.

Looking online the pressure should be 35.8! Although it doesn't specify wheel size. I think I'll Google translate my manual tomorrow!

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The door placard is for the OEM tyres. Newer tyres are designed to give a comfortable ride at much higher pressure and running them at the OEM spec tyre pressures may be under-inflation. See here for more info: http://www.agcoauto.com/content/news/p2_articleid/61

TL;DR start at 10% below the maximum rated pressure on the sidewall and adjust down until the ride is comfortable enough.

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Mark, that is an interesting article and the first time I have ever seen in writing a recommendation to deviate from the manual. Thanks for posting.

Just looked at the side wall of my new Avons and the max is 50psi. Do we know if that is a max cold setting or is it the max that tyre in use must never exceed?

To drive my car at 45psi cold setting [50 less 10%] for sustained high speeds would worry me. My door pillar gives 33psi for low load up to 210kph.  

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@GrahamG Max that the tyre should never exceed. That's why Louis's article says start at 10% below the max rating, to allow for the pressure to rise when the tyre heats up.

I run my RX at 40psi all around, i think the max is 51. 40 gives a nice balance between tyre wear and ride comfort.

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@GrahamG Also just to mention that the reason I ended up discovering that article was after I'd had a service on a previous car and been told that my tyres had signs of outer edge wear because they were under-inflated even though I'd religiously set them to the pressures on the door placard every few weeks.

I asked Louis about this and he pointed me at his article and explained that the door placard is for OEM tyres but newer tyres may require more pressure.

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I've always stuck to the recommended pressures, even on a 12yr old car and many tyre changes. Never had an abnormal wear problem.

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I have been cold setting the excellent 18" Hankook Ventus on my '06 RX350 at the placarded 32psi and over 6 years the pattern of wear shows correct inflation. Durability looks good for  over 30,000 miles down to 4mm which is minimum tread for me.

The manufacturer's max for these tyres is 51psi and what this discussion suggests is that our tyres are capable of a much wider range of pressures than I had thought.

I will bump up the pressure a couple of psi on both cars if only because it allows a greater margin over what might be considered a minimum value.

 

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Manual says 35 psi plus a bit more if going heavy and fast. 

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27 minutes ago, MLW said:

Manual says 35 psi plus a bit more if going heavy and fast. 

Thanks, so I've more or less been right with it. I really must think about finding a manual. I've got an online version but it's a tad fiddly.👍

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