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Looking for the right pressures for the LS430 running Dunlop 225/55/17 i found a thread from this site saying 35 PSI is the magic number all round, so off i pop and put in 35 all round, what i did find was from cold the Tyre pressures where all over the place from 21 back to 32 front on each corner ??? don't know whats happened there only 5 weeks out of the dealership, keep my eye on them from now on, the car had felt a liyyle different, just a little and that's what gave way to the trip,

What a difference again to the car, smoother, quieter , firmer, handling stands better in the road my question is.

1 why where the pressures all over the place

2 is 35psi all round the magic number

3 what are your pressures

any further recommendations on pressures

Regards Mark

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I put 35 in mine all round.

Pressure loss is normally due to corrosion around the bead sealing area of the rim, especially on alloy wheels, sometimes bead sealer helps or the fitter should go over the area with a wire brush of some type to remove as much corrosion as possible before fitting the tyre.

There are obviously other possible causes, leaking valves, a slow punction or vandals "adjusting" your tyre pressures.

Now you have them all correct keep monitoring them at least on a weekly basis.

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I put 37 all round my 430 and it rides well and the tyres wear uniformly- they always leak a little. I check mine every couple of weeks and always have to pump them up a little. Make sure the fronts don't go low or you will wear the outer edges of the tread. Also make sure you check the alignment especially as the car ages - obvious but easy to forget (I did).

Bren

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Hi all, the car had a 4 wheel alignment before i bought it from Lexus, @ 35 the car rides a little firmer but a lot better,

so we have

31

35

37

any advance on these pressures my car sits,drives,handles so much better in normal mode, i put into sport and power and it was like a sports car handling really good.

Regards Mark

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A very positive sign today on MPG my average for the short school runs i do and a bit of tripping around was a paltry 14.9 mpg today i looked at the average on the computer and 19.4 mpg wow what a difference since the tyre pressure alteration.,

Regards Mark

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A very positive sign today on MPG my average for the short school runs i do and a bit of tripping around was a paltry 14.9 mpg today i looked at the average on the computer and 19.4 mpg wow what a difference since the tyre pressure alteration.,

Regards Mark

Thats a big improvement - i used to get 13 on my 400

Im going to check mine tommorrow

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A very positive sign today on MPG my average for the short school runs i do and a bit of tripping around was a paltry 14.9 mpg today i looked at the average on the computer and 19.4 mpg wow what a difference since the tyre pressure alteration.,

Regards Mark

You need to be careful with the computer - the only real way to check you consumption is with a pencil and paper when you fill up. I have a 430 and the computer average is almost always 22MPG. If I can restrain myself and drive at 70 on the motorway then I can get it over 30MPG (does not happen often) - I have a mate who plods around in a 400 and returns really good MPG figures. On short runs and round town 16 is more like it for my 430. I am a little impatient and my heavy right foot probably costs me money so I went for an LPG conversion - that is almost half price motoring after you have paid off the capital costs.

The type of tyre you use will also affect your fuel consumption - cheap tyres often have a high rolling resistance. Also winter tyres work well in the winter and are safer - you will reduce your stopping distance in the cold.

Bren

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A very positive sign today on MPG my average for the short school runs i do and a bit of tripping around was a paltry 14.9 mpg today i looked at the average on the computer and 19.4 mpg wow what a difference since the tyre pressure alteration.,

Regards Mark

You need to be careful with the computer - the only real way to check you consumption is with a pencil and paper when you fill up. I have a 430 and the computer average is almost always 22MPG. If I can restrain myself and drive at 70 on the motorway then I can get it over 30MPG (does not happen often) - I have a mate who plods around in a 400 and returns really good MPG figures. On short runs and round town 16 is more like it for my 430. I am a little impatient and my heavy right foot probably costs me money so I went for an LPG conversion - that is almost half price motoring after you have paid off the capital costs.

The type of tyre you use will also affect your fuel consumption - cheap tyres often have a high rolling resistance. Also winter tyres work well in the winter and are safer - you will reduce your stopping distance in the cold.

Bren

I agree but a sudden change in MPG + in my favor was quickly correlated with the petrol gauge needle not moving, i know this is not scientific, but i noticed this and that's why i checked it.

Before the tyre inflation the car started supping juice faster than a 747, but the shoddy tyre pressures i found might account for this, also remember that you get fewer MPG from LPG and the cars computer works on the petrol system only not on the Lpg system so your figures could be a little out, i am not expecting massive gains but realistically 5-7 miles + per gallon from a simple tyre inflation for me anyway is a cheap and well worth the time checking fix.

Regards Mark

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I have 18" rims and had 31 all round. Following a new tyre they had front ones at 36 and felt much better. It's still the only car I have ever owned where the fuel gauge moves visibly between here and the shops but I can forgive it every time I sit in it and waft around in splendid comfort!

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I have 18" rims and had 31 all round. Following a new tyre they had front ones at 36 and felt much better. It's still the only car I have ever owned where the fuel gauge moves visibly between here and the shops but I can forgive it every time I sit in it and waft around in splendid comfort!

With Lexus being so reliable they rarely break down and need recovery so we never get that free transport on the back of a relay truck where a Lexus LS400 could potentially cover 200 miles without using a single drop of petrol! If I was ever in that position I would insist still sitting in the LS on the back of the transporter. :lol:

All I can really add to the tyre pressure debate is both under and over inflation will cause abnormal wear to tyres so hit middle ground and check the tread wear frequently.

If they start wearing more on both outer tread areas they are under inflated and if the centre section is wearing faster than the outer they are over inflated.

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When I had the 4 wheel tracking done earlier this year they recommended 37 fronts and 35 rears, the fronts have a lot of weight on them with that lovely V8 sitting on them hence the difference. Mike

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When I had the 4 wheel tracking done earlier this year they recommended 37 fronts and 35 rears, the fronts have a lot of weight on them with that lovely V8 sitting on them hence the difference. Mike

I can go with that 37,35, as my old E300TD the old 3 lit diesel lump V6 sits 32 front 29 rear with self leveling suspension, have you noticed any uneven wear on the fronts at 37.

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When I had the 4 wheel tracking done earlier this year they recommended 37 fronts and 35 rears, the fronts have a lot of weight on them with that lovely V8 sitting on them hence the difference. Mike

I can go with that 37,35, as my old E300TD the old 3 lit diesel lump V6 sits 32 front 29 rear with self leveling suspension, have you noticed any uneven wear on the fronts at 37.

Yes I had a new pair of tyres on the front and they were ruined. This was after I had been to two places who insisted I didn't need the 4 wheel tracking and just did the old fashioned method which of course was useless.

I eventually found a place that didn't mind if I spent my money on 4 wheel tracking even if I didn't need it. They took over an hour sorting it and the result was perfect. Steering wheel was back in its proper position I bought two more tyres and there is no sign of any uneven wear 7,000 miles on.

Yes I did say to them about the position of the steering wheel and the excuse from one was "because you have electric steering it will take a while for the cars computer to compute this and correct it" Words failed me.

Why is this country full of cowboys giving out rubbish info and mucking your cars up? I could have used much stronger words there but don't know if we have any vicars as members.

Mike

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I've seen some valve caps that give a visual indication of tyre pressure, priced around £15,no idea how well they work though.

Got some of these chaps on my motorcycle, different pressure front and back so have to get the correct units, they show green caps when correctly inflated and change to yellow and red when pressure is lost, also show yellow and red when over inflated.

They have worked very well and accurate on several bikes for several years :)

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After reading the threads I am now a bit worried and confusedI have got a 97-400 on kumho tyres 225-60r-16-98w, the book says 30psi for them.What do you gentlemen recommend I use, any advice is welcome.

On my LS430 (204K miles) I am running KUMHO ECSTA SPT 225/55R17 101WXL tyres and put 37 all round. These are the best tyres I have ever used on the car in 10 years.

I had 3 LS400s and would not put less than 30 in and used to put in 33 all round - just make sure you are not seeing any feathering on the edges of your front tyres that will indicate low pressure. I lived in Milton Keynes when I owned 2 of the 400s and the round abouts killed tyres and as soon as I moved out my front tyre wear dropped dramaically.

Bren

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After reading the threads I am now a bit worried and confusedI have got a 97-400 on kumho tyres 225-60r-16-98w, the book says 30psi for them.What do you gentlemen recommend I use, any advice is welcome.

On my LS430 (204K miles) I am running KUMHO ECSTA SPT 225/55R17 101WXL tyres and put 37 all round. These are the best tyres I have ever used on the car in 10 years.

I had 3 LS400s and would not put less than 30 in and used to put in 33 all round - just make sure you are not seeing any feathering on the edges of your front tyres that will indicate low pressure. I lived in Milton Keynes when I owned 2 of the 400s and the round abouts killed tyres and as soon as I moved out my front tyre wear dropped dramaically.

Bren

Just for future reference brenadan - are these kumhos quite and smooth?
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After reading the threads I am now a bit worried and confusedI have got a 97-400 on kumho tyres 225-60r-16-98w, the book says 30psi for them.What do you gentlemen recommend I use, any advice is welcome.

On my LS430 (204K miles) I am running KUMHO ECSTA SPT 225/55R17 101WXL tyres and put 37 all round. These are the best tyres I have ever used on the car in 10 years.

I had 3 LS400s and would not put less than 30 in and used to put in 33 all round - just make sure you are not seeing any feathering on the edges of your front tyres that will indicate low pressure. I lived in Milton Keynes when I owned 2 of the 400s and the round abouts killed tyres and as soon as I moved out my front tyre wear dropped dramaically.

Bren

Just for future reference brenadan - are these kumhos quite and smooth?

Hi mark

These Kumhos are pretty smooth when warm and quiet on a decent road. My 430 has the performance pack and has never been as quiet as a 400 on the original Dunlops. I will buy these tyres again because they are quiet, wear well and are good in the wet.

Bren

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Sadly Dunlop no longer make the ( D8Z is it ? ) tyres for the LS400 and haven't for some time now .............. but I heard from Treadmark Canterbury that Dunlop make Falkens and it is those that I will be using for the future.

I read that Dunlop actually developed the original tyre specifically for the LS400 and I also read that Falkens are quite an acceptable replacement and give ok performance too.

Malc

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