Tyre pressures

[Bill Dawes]

Hi all, playing about with all the settings today on my UX Takumi, came across the tyre pressure monitor readings, all read 2.7 Bar apart from one one which was 2.6.

Then decided to check what they were supposed to be, plate inside the door frame said 2.3 Bar.

Double checking in manual (not an easy thing, the 'contents' section is far from comprehensive) it too said 2.3 Bar, my tyres are the 18" run flat ones.

Now all this doesn't actually surprise me, my previous car, a Kia Niro, always had its tyres inflated well over the official pressure, why do this, it's as if they just have a 'err on the high' side default figure rather than looking up all the combination of models and tyre options. I will give it a try on 2.3 Bar to see what it does to the ride when Iv'e got time to faff about with resetting the monitors, not a simple just press a button job reading the manual.

Anyone else found this issue of dealer set pressures.

I also noticed that just one set of pressures were quoted, my previous cars gave different figures for different loads.

Bill D.

[David Claridge]

I have a UX F Sport with 18 inch run flats. Last winter on really cold days my tyre pressure warning light came on at 2.2 bar on one tyre and went out at 2.3 bar. At the service in June I asked the dealer to set the warning lower. All are now reading 2.4 cold and 2.6 after driving and the ride is fine. I will have to wait until winter to see if they reset the warning or just increased the pressures.

[Rabbers]

I have often noticed slight deviations from recommended pressures after servicing, which I then habitually rectify within the next couple of days. I’m glad to say, on the other hand, that all four are always spot on after seasonal winter/summer tyre changes done by my trusted tyre dealer.  In the certainty that the recommended pressures were figured out as optimal by Lexus at the car’s development stage, I try and maintain them at all times, perhaps adding 0.1 to the rears when embarking on a long motorway drive with a full boot.

[Bill Dawes]

Yes I agree that tyre pressures will change with temperature, increase with increase in temperature and vice versa.

Standard spec is with cold tyres and my check was with pretty much cold tyres but will do a 'scientific' check when I have time. On my previous cars  I towed a caravan and needed to increase pressures then but don't now, just as well the UX has not got  good towing spec.

Bill D.

[Harrier Man]

10 hours ago, Bill Dawes said:

Hi all, playing about with all the settings today on my UX Takumi, came across the tyre pressure monitor readings, all read 2.7 Bar apart from one one which was 2.6.

Then decided to check what they were supposed to be, plate inside the door frame said 2.3 Bar.

Double checking in manual (not an easy thing, the 'contents' section is far from comprehensive) it too said 2.3 Bar, my tyres are the 18" run flat ones.

Now all this doesn't actually surprise me, my previous car, a Kia Niro, always had its tyres inflated well over the official pressure, why do this, it's as if they just have a 'err on the high' side default figure rather than looking up all the combination of models and tyre options. I will give it a try on 2.3 Bar to see what it does to the ride when Iv'e got time to faff about with resetting the monitors, not a simple just press a button job reading the manual.

Anyone else found this issue of dealer set pressures.

I also noticed that just one set of pressures were quoted, my previous cars gave different figures for different loads.

Bill D.

Re your last point, I raised this here, 

. It still seems odd to me that Lexus provide only one pressure for all situations.

[fivish]

The B pillar sticker for my 11/2021 UX250h with Bridgestone Turanza T005(a) says 2.5 bar front and rear. Thats 36.26 PSI. Can't seem to change the display from bar to psi.

 

 

[Lmafudd]

My warning light alerted me on Sunday when we had a slight frost. This isn't abnormal in previous cars when the weather changes. I had 4 new tyres a couple of weeks ago and although the plate states 2.3 bar I actually like to start slightly low as the tyres get firmer when the temperature from road friction does its stuff. By the time everything was warmed up the monitor reported 2.3 bar on all tyres but the front nearside still showed yellow on the graphic. Ironically, when first started, they all showed 2.1 bar except for the front nearside that started at 2.2 and this was the one that showed as 'low'!

I have reset the pressure switch and will see how it progresses but I may have to add a little pressure for these colder times!

[LenT]

3 hours ago, Lmafudd said:

I actually like to start slightly low as the tyres get firmer when the temperature from road friction does its stuff.

As it happens, the recommended tyre pressures by both car and tyre makers are based on those recorded on a cold tyre.  The use of a slightly raised pressure would be indicated in the event of unusually heavy loads.

This is an extract from a Continental Tyres web page on the subject.  I have always considered that the ‘recommended’  pressure is the target figure when cold, on the basis that it is the optimum starting point as neither tyre nor car maker can control the varying weather conditions or driving styles that the tyre may face - even in the course of the same journey.

 

Continental Tyres:

Cold tyres. You’ll get a more accurate reading if you check the pressure when the tyres are cold, before the outside temperature rises and the tyres are exposed to direct sunlight. If the outside temperature increases by 10 degrees Celsius, the tyre pressure will increase by 1.6 PSI. In winter, in some climates, tyres could experience a drop of up to 5 PSI.

[Lmafudd]

4 hours ago, LenT said:

As it happens, the recommended tyre pressures by both car and tyre makers are based on those recorded on a cold tyre.  The use of a slightly raised pressure would be indicated in the event of unusually heavy loads.

This is an extract from a Continental Tyres web page on the subject.  I have always considered that the ‘recommended’  pressure is the target figure when cold, on the basis that it is the optimum starting point as neither tyre nor car maker can control the varying weather conditions or driving styles that the tyre may face - even in the course of the same journey.

 

Continental Tyres:

Cold tyres. You’ll get a more accurate reading if you check the pressure when the tyres are cold, before the outside temperature rises and the tyres are exposed to direct sunlight. If the outside temperature increases by 10 degrees Celsius, the tyre pressure will increase by 1.6 PSI. In winter, in some climates, tyres could experience a drop of up to 5 PSI.

That may be the case but I found the car was quieter and more comfortable starting slightly low when running the dreaded run-flats. Now I've changed to standard tyres I will probably go to the 2.3 bar the system states. Thanks for the useful info though.

[stevewagster]

On 8/26/2022 at 10:45 PM, Bill Dawes said:

Hi all, playing about with all the settings today on my UX Takumi, came across the tyre pressure monitor readings, all read 2.7 Bar apart from one one which was 2.6.

Then decided to check what they were supposed to be, plate inside the door frame said 2.3 Bar.

Double checking in manual (not an easy thing, the 'contents' section is far from comprehensive) it too said 2.3 Bar, my tyres are the 18" run flat ones.

Now all this doesn't actually surprise me, my previous car, a Kia Niro, always had its tyres inflated well over the official pressure, why do this, it's as if they just have a 'err on the high' side default figure rather than looking up all the combination of models and tyre options. I will give it a try on 2.3 Bar to see what it does to the ride when Iv'e got time to faff about with resetting the monitors, not a simple just press a button job reading the manual.

Anyone else found this issue of dealer set pressures.

I also noticed that just one set of pressures were quoted, my previous cars gave different figures for different loads.

Bill D.

I agree Bill, all the cars we have had over the years have had different load spec for one passenger, full occupancy and loaded and some with high speed driving, so this is new! also I have just written of my experience with my tyre pressures below!

My car is now coming up to three moths old and the tyre warning light has always been on even though it has spent around 6 weeks in the dealers, I decided to check it out even though I'm pretty certain that it's an electrical fault, the dash just shows as blank where the tyre pressures should be.

I decided to get out there on my knees and physically check the pressures: front o/s/f 46 psi -3,2 bar, n/s/f 38psi - 2.6 bar, rear o/s/f 32psi - 2.2 bar, n/s/r 34 psi - 3.3 bar, they are now 34 psi - 2.3 bar all round, i have re-set the dash and awaiting to see if I get a correct display and the warning light goes out.

My thoughts turn to Lexus yet again for not bothering to check the pressures at all. The car drove reasonably straight with a very slight pull to the left but camber could be the cause on that but a very firm ride, which I assume was due to the run flats of which I'm not a big fan of, anyway, I can't wait to check it out tomorrow after a drive out to see if it has re-set and the tyre pressures are displayed and the light is out..

[stepppy]

I test drove an NX recently with 18 inch wheels which I thought would give a nice cushy ride, but found it to be really quite firm.  I took the car home to try it in the garage and whilst I was there I checked the tyre pressures and they were grossly over inflated.  I put them to the correct pressures and it was like night and day.

I always manually check my tyre pressures after a service as they always inflate them to max load capacity.

Not sure why they do this, it would make more sense to inflate them to a middle ground if they do not want to have them at the lowest setting.  I know some people like to over inflate their tyres for better economy, but I would rather have a nice ride.

[Roger Bill]

I think most new cars are delivered with tyres pumped to a higher than normal pressure. Possibly to minimise flat spots on tyres if the car is stored for long periods. However, tyre pressures should be set correctly as part of pre-delivery inspection.

[stevewagster]

4 hours ago, Roger Bill said:

I think most new cars are delivered with tyres pumped to a higher than normal pressure. Possibly to minimise flat spots on tyres if the car is stored for long periods. However, tyre pressures should be set correctly as part of pre-delivery inspection.

You might think so!

 

[Rabbers]

There was another LOC post on this subject some years ago, and as I was at my dealership waiting for my car to be serviced, I mentioned it to the workshop manager, who is also responsible for inspecting new cars on their receipt into stock.  He confirmed that new Lexus (though not in his experience Toyota) cars arrive with tyres overinflated by 0.2-0.3BAR or more and therefore require correction before sale (which does not mean that all dealers are efficient or conscientious enough to do it).

He could offer no explanation beyond the probability that the potentially huge fluctuations in temperatures during maritime transportation from Japan to all parts of the world might involve the risk of a significant reduction of tyre pressures and therefore of prospective damage to the tyres themselves not only when the cars are driven off the boats but also during the further series of reconsignments and reloadings they undergo before reaching their final destinations.

[Don C]

15 hours ago, Rabbers said:

There was another LOC post on this subject some years ago, and as I was at my dealership waiting for my car to be serviced, I mentioned it to the workshop manager, who is also responsible for inspecting new cars on their receipt into stock.  He confirmed that new Lexus (though not in his experience Toyota) cars arrive with tyres overinflated by 0.2-0.3BAR or more and therefore require correction before sale (which does not mean that all dealers are efficient or conscientious enough to do it).

He could offer no explanation beyond the probability that the potentially huge fluctuations in temperatures during maritime transportation from Japan to all parts of the world might involve the risk of a significant reduction of tyre pressures and therefore of prospective damage to the tyres themselves not only when the cars are driven off the boats but also during the further series of reconsignments and reloadings they undergo before reaching their final destinations.

Are you sure about those numbers?   Toyotas from Japan come with around 20psi too much pressure which is about 1.4 bar.  It’s normal.  It makes them more stable on the ship and prevents tyre flatting.  

[Rabbers]

4 hours ago, Don C said:

Are you sure about those numbers?   Toyotas from Japan come with around 20psi too much pressure which is about 1.4 bar.  It’s normal.  It makes them more stable on the ship and prevents tyre flatting.  

I would guess that if factory pressures are set higher for Lexus it might be because all or almost all units are shipped from Japan whereas most Toyota delivery distances are relatively much shorter and conditions prospectively less onerous. 

[ColinBarber]

Most manufacturers use higher pressures if transporting via a RoRo as vehicles are lashed down via the wheels and therefore the tyres have additional load on them.

Even if pressures were set at normal recommended levels, temperature differences between countries or just the time lapse between manufacture and delivery would mean the pressures were unlikely to be suitable, hence why they should be corrected during PDI. 
 

If you are receiving vehicles with incorrect pressures then someone isn’t doing their job correctly or are using miscalibrated equipment.