Tire Pressure
08-29-12, 04:04 PM
#16
Oh yes they do...they just leak slower. My tires were filled with nitrogen by my dealer when new. Every 3 or 4 weeks they will all lose 1-2 lbs. I fill them back to the recommended 33 p.s.i. (cold inflation pressure) with my compressor, and a few weeks later they will be another 1-2 lbs. low. A couple of pounds makes a remarkable difference in ride and handling, as any Nascar fan can tell you.
Note to OP: With a cold inflation pressure of 33 p.s.i., the pressures will increase up to 37-38 p.s.i. as the tires heat up at speed. After driving on the freeway for 4-5 miles they will stabilize at around 37 p.s.i., then slowly reduce back to 33 p.s.i. after a couple of hours in the garage.
Note to OP: With a cold inflation pressure of 33 p.s.i., the pressures will increase up to 37-38 p.s.i. as the tires heat up at speed. After driving on the freeway for 4-5 miles they will stabilize at around 37 p.s.i., then slowly reduce back to 33 p.s.i. after a couple of hours in the garage.
Last edited by rjm; 08-29-12 at 04:09 PM.
08-29-12, 07:46 PM
#17
Oh yes they do...they just leak slower. My tires were filled with nitrogen by my dealer when new. Every 3 or 4 weeks they will all lose 1-2 lbs. I fill them back to the recommended 33 p.s.i. (cold inflation pressure) with my compressor, and a few weeks later they will be another 1-2 lbs. low. A couple of pounds makes a remarkable difference in ride and handling, as any Nascar fan can tell you.
Note to OP: With a cold inflation pressure of 33 p.s.i., the pressures will increase up to 37-38 p.s.i. as the tires heat up at speed. After driving on the freeway for 4-5 miles they will stabilize at around 37 p.s.i., then slowly reduce back to 33 p.s.i. after a couple of hours in the garage.
Note to OP: With a cold inflation pressure of 33 p.s.i., the pressures will increase up to 37-38 p.s.i. as the tires heat up at speed. After driving on the freeway for 4-5 miles they will stabilize at around 37 p.s.i., then slowly reduce back to 33 p.s.i. after a couple of hours in the garage.
09-03-12, 01:43 PM
#18
09-04-12, 06:01 AM
#19
I have this problem as well but i think a little more extreme. As part of my deal when i bought the car the dealer actually swapped my 20"s (255/30/20) from my '06 GS to the new ride. I remember them having a little trouble programming the TPMS. Not sure why as we swapped the TPMS when we swapped out the wheels/tires. Anyway, when i initially got my car back from the dealer, all my tires were set to 30. I thought it was a little low but i decided to go with the dealer setting. Drove home,close to 50 miles away from the dealer, and the ride was smooth but i could tell the ride was bumpier than i would have liked. So, as soon as i got home, put the tires back to 39-40 and got on the highway and she drove like a dream. About a week later i could see that the tires were slowly losing PSI. I would say when i do normal daily driving i lose about 1/2 PSI a day, maybe a little less. So about every 10 days or so i am having to fill my tires back up. The problem is i go on week long business trips a couple times a month, leave Sunday, come back friday, when i dont drive her daily she loses a little over 1 PSI a day. So i leave Sunday with her at 39-40 PSI, come back Friday/Saturday and shes sitting at 28/29 PSI. I havent taken her into the dealer yet as this is a minor inconvenience as i wash her almost weekly and fill up the tires the same time. Figured i would wait until the 5k service to have her checked out. I wasnt sure if the TPMS setting the dealer put on her, 30 PSI, means that all tires try to revert back to this PSI even if you overfill? I also read online that constant air leakage like the one i described above could be damaged valve stems. Either way im sure the dealer will be able to take care of it once i hit 5k, only sitting at 2.5k, bought her end of April.
11-01-12, 05:51 PM
#20
I noticed that my TPMS is not accurately displaying the tires' psi. Is there a way to reset the sensors so that the readings will be correct? Before the weather turned colder here in TX, the psi was about 36-37, and now that the weather is cooler, the psi reads 38-39. I know that the psi should be lower, as there is a gradual leak of pressure over time (~1 month). Please let me know if you have information on this. Thanks.
11-01-12, 09:27 PM
#21
Instructor
I noticed that my TPMS is not accurately displaying the tires' psi. Is there a way to reset the sensors so that the readings will be correct? Before the weather turned colder here in TX, the psi was about 36-37, and now that the weather is cooler, the psi reads 38-39. I know that the psi should be lower, as there is a gradual leak of pressure over time (~1 month). Please let me know if you have information on this. Thanks.
11-02-12, 09:25 AM
#22
Do you guys need to have tire rotations done at your Lexus dealer in order to keep TPMS readings in sync with tires' new positions? If not, how does the system "know" the new positions of the tires so it can display their PSIs in the correct location on the graphical display? Thanks in advance for info.
11-02-12, 03:42 PM
#23
11-02-12, 04:13 PM
#24
Look in your manual. It's not behind a removable panel. It is located in a recess below the steering wheel. It's kind of hard to find unless you knell down, see where it is, and feel for it. With the ignition on, but the car not running, press it until you get the readout in the display. Instructions are in the manual.
11-02-12, 05:03 PM
#25
The tire pressure monitor on your display should be used as a reference. You should check the pressure in your tires once per week with a pressure gauge for many reasons. Why would you ever need your dealership's help to do this? I used to check my dad's tires for him when I was 5 years old. My goodness.
If you have an F-Sport you have fairly low profile tires. I have found over the years that low profile tires need more care in terms of checking the pressure.
If you have an F-Sport you have fairly low profile tires. I have found over the years that low profile tires need more care in terms of checking the pressure.
do you guys check your tire pressure monitor? i've been to lexus twice to correct my tire pressure. i checked again the other day and it's steady at 32/33. i know that's the wrong pressure,,, and i've also taken into account the temp. etc. i always let the tires heat up and check and it stays steady at 32/33. and i've been doing that everyday now for a week. before i drive off the monitor may say 31/32, and sometimes it's all over the place, but after i've driven for a while it's steady at 32/33. i'm tired of going to Lexus for these minor issues. it makes you wonder if they really know what they're doing. oh well,,,, guess i'll be making another trip to Lexus. if you have to go back 2 or 3 times after buying a new car,,, okay,,, but after that it really becomes a PITA. we shouldn't be going back at all. just getting some things off my chest fellas.
11-02-12, 05:44 PM
#26
Look in your manual. It's not behind a removable panel. It is located in a recess below the steering wheel. It's kind of hard to find unless you knell down, see where it is, and feel for it. With the ignition on, but the car not running, press it until you get the readout in the display. Instructions are in the manual.
11-02-12, 09:58 PM
#27
The tire pressure monitor on your display should be used as a reference. You should check the pressure in your tires once per week with a pressure gauge for many reasons. Why would you ever need your dealership's help to do this? I used to check my dad's tires for him when I was 5 years old. My goodness.
For starters, the pressure sensors in your tires are more accurate than 99% of tire gauges in general use. That POS stick gauge your average "mechanic" uses is +/-15% or worse depending on a number of factors. Your in-tire sensors are typically accurate to +/- 1 PSI or better. So you may wish to reconsider your life-long tire checking procedure.
As to my other question, I was asking how the vehicle smarts keeps track of which tire is where. Consider each tire placed on the vehicle at the beginning of time starting at LF then RF then RR then LR. If this mounting sequence is the default, then the vehicle should be able to register the tires properly in order to display PSIs at correct locations. Then you take your car to the tire man and he rotates your tires back to front both sides. If he does not follow the "official" mounting sequence, your PSIs will not be in the correct positions in the display. How are we to maintain the tire/position correspondence if there are mounting procedures or sensor reset/activation steps we know nothing about?
11-03-12, 07:20 PM
#28
Let me know the source of your TPMS knowledge such as a link or a reference of some sort. I can tell you for certain that I 100% disagree with you based on my experience.
I have a nice digital tire gauge that has a specified accuracy within .05 PSI and the readings are in .5 PSI increments. The most my gauge can be off is by .55 PSI.
I have on several occasions compared my old manual gauge, my digital gauge, and my TPMS readings. TPMS is always off by 2-3 PSI. My manual gauge and my digital gauge are always spot on.
I have done this with my current 2013 GS350, my wife's current 2013 GS350, my 2012 GX460, my 2009 IS350, etc. TPMS has always been the least accurate.
Car companies are not going to spend the $$$ to place super accurate pressure sensors on our wheels.
Sorry to rain on your parade. Have a good night.
I have a nice digital tire gauge that has a specified accuracy within .05 PSI and the readings are in .5 PSI increments. The most my gauge can be off is by .55 PSI.
I have on several occasions compared my old manual gauge, my digital gauge, and my TPMS readings. TPMS is always off by 2-3 PSI. My manual gauge and my digital gauge are always spot on.
I have done this with my current 2013 GS350, my wife's current 2013 GS350, my 2012 GX460, my 2009 IS350, etc. TPMS has always been the least accurate.
Car companies are not going to spend the $$$ to place super accurate pressure sensors on our wheels.
Sorry to rain on your parade. Have a good night.
Brad,
For starters, the pressure sensors in your tires are more accurate than 99% of tire gauges in general use. That POS stick gauge your average "mechanic" uses is +/-15% or worse depending on a number of factors. Your in-tire sensors are typically accurate to +/- 1 PSI or better. So you may wish to reconsider your life-long tire checking procedure.
As to my other question, I was asking how the vehicle smarts keeps track of which tire is where. Consider each tire placed on the vehicle at the beginning of time starting at LF then RF then RR then LR. If this mounting sequence is the default, then the vehicle should be able to register the tires properly in order to display PSIs at correct locations. Then you take your car to the tire man and he rotates your tires back to front both sides. If he does not follow the "official" mounting sequence, your PSIs will not be in the correct positions in the display. How are we to maintain the tire/position correspondence if there are mounting procedures or sensor reset/activation steps we know nothing about?
For starters, the pressure sensors in your tires are more accurate than 99% of tire gauges in general use. That POS stick gauge your average "mechanic" uses is +/-15% or worse depending on a number of factors. Your in-tire sensors are typically accurate to +/- 1 PSI or better. So you may wish to reconsider your life-long tire checking procedure.
As to my other question, I was asking how the vehicle smarts keeps track of which tire is where. Consider each tire placed on the vehicle at the beginning of time starting at LF then RF then RR then LR. If this mounting sequence is the default, then the vehicle should be able to register the tires properly in order to display PSIs at correct locations. Then you take your car to the tire man and he rotates your tires back to front both sides. If he does not follow the "official" mounting sequence, your PSIs will not be in the correct positions in the display. How are we to maintain the tire/position correspondence if there are mounting procedures or sensor reset/activation steps we know nothing about?
11-03-12, 09:15 PM
#29
Lexus Champion
Agreed. I would rely on my tire guage before I would ever rely on TPMS. Just filled my tires today... 36 front, 37 rear. My TPMS shows slightly lower, but I'm not concerned.
11-03-12, 09:34 PM
#30
As I said, 99% of gauges in common use are garbage. Congratulations on your membership in the 1%. You have an accurate, precise instrument (as do I). Keep your eyes (and mind) open for the next while and see what is actually used at dealerships, tire shops, quick lubes, etc. and you'll see how the great unwashed measures. As far as links, get off your butt and dig them up yourself. TPMS sensor spec sheets are widely available online and specific (in)accuracies of different gauges can be found in the stores where they are sold (most auto parts stores).