Drivers should ignore that chart. Those compensation values are to be used by service professionals when working inside a heated building. Pressure compensation is not necessary when inflating cold tires while outside.
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You FORGOT to post the important info about that chart.
Here is an example of the chart in action:
A vehicle that has been parked overnight outside the shop has cold tires, and tire pressures are set to 31.9 psi. The shopās inside temperature is 68Ā° F and the lowest expected ambient temperature in the local area is to be 14Ā° F.
1. Subtract the expected lowest temperature (14Ā° F) from the shop temperature (68Ā° F) = 54Ā° F.
2. Using the chart, find the intersection of the cold tire line at the point corresponding to 54Ā° F and read the value on the tire pressure change axis. In this case, it would be about 4.9 psi.
3. The tires, including the spare tire, should be filled to: 31.9 + 4.9 psi = 36.8 psi.
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Nevada_645 explained that to me already, right above you, thank you.
Porche and BMW use in their tpms system 20 degrC/ 68 degrF index temperature, wich they assume determined needed pressure for load and speed for the different settings , to be needed for.
On screen they give besides the actual pressure, also the recomended pressure for the setting ( sport, comfort fi) calculated from index temperature to temperature of gascompound in tire, also receved from the sensors in tire.
So I suspect they also hang the low pressure warning on that, so lesser false low pressure warnings , as you now have.
So if calculated back to 68 degrF ( make it 70 for easy calculating) its the 32 psi you determined needed, chanche nothing.
Basic idea is that main goal of pressure determination, is to give tire a deflection , so heatproduction , that wont overheat any part of tire-material, driving the speed constantly, for wich its determined.
When hotter in and out tire, lesser cooling down is compensated by lesser heatproduction by lesser deflection the higher pressure gives, so tire-material still not comes above its critical temperature of about 250 degrF, at wich it hardens and beginning internal cracks are created, allowed ā ZERO ā times in tires use. So never blead down cold or hot pressure on a 100 degrF day,
When cold out and in , like your 20 degrF, the other way around. But then you are allowed to highen up to your 32 psi for reasons of fuel/energy-saving and riding quality. Tire-material only stays cooler then.
Calculating by head with the rule of tumb of 1 psi per 10 degrF is acurate enaugh for the goal .
But I made list for index-temperature of 70 degrF , then you find your 32 psi to give 11.5 degrF at wich pressure changes 1 psi.
70degrF./degrF/psi
20 psi/ 15,5F/psi
21 psi/ 15F/psi
22 psi/ 14,5F/psi
23 psi/ 14 F/psi
24 psi/ 13,5F/psi
25 psi/ 13,5F/psi
26 psi/ 13 F/psi
27 psi/ 12,5 F/psi
28 psi/ 12,5 F/psi
29 psi/ 12 F/psi
30 psi/ 12 F/psi
3 1psi/ 11,5 F/psi
32 psi/ 11,5 F/psi
33 psi/ 11 F/psi
34 psi/ 11 F/psi
35 psi/ 10,5 F/psi
36 psi/ 10,5 F/psi
37 psi/ 10 F/psi
39 psi/ 10 F/ps
40 psi/ 9,5 F/psi
42 psi/ 9,5 F/psi
43 psi/ 9 F/psi
45 psi/ 9 F/psi
46 psi/ 8,5 F/psi
49 psi/ 8,5 F/psi
50 psi/ 8 F/psi
53 psi/ 8 F/psi
54 psi/ 7,5 F/psi
58 psi/ 7,5 F/psi
59 psi/ 7 F/psi
63 psi/ 7 F/psi
64 psi/ 6,5 F/psi
70 psi/ 6,5 F/psi
71 psi/ 6 F/psi
77 psi/ 6 F/psi
78 psi/ 5,5 F/psi
86 psi/ 5,5 F/psi
87 psi/ 5 F/psi
96 psi/ 5 F/psi
97 psi/ 4,5 F/psi
109 psi/ 4,5 F/psi
110 psi/ 4 F/psi
126 psi/ 4 F/psi
127 psi/ 3,5 F/psi
148 psi/ 3,5 F/psi
149 psi/ 3 F/psi
177 psi/ 3 F/psi
Good Grief jadatis. Talk about making something simple for the average person ( look at door jamb ) complicated,
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All I can make of it is an Empire State Building high stack of numbers 
I appear to be late to the party. And youse guys didnāt wait for me. I am crushed!
First, the proper tire pressure is listed on the vehicle tire placard. That pressure is applicable for whatever the ambient temperature is. If the screenshot of the dash is to be believed, the tire pressure was set when it was 90 degrees F.
The OP wants to know what pressure to set when he next fills the tires up - REGARDLESS of the weather!! Answer, there isnāt one. You have to set the pressures based on what you are anticipating the lowest temperature in the next interval before the next tire maintenance scheduled.
So assuming he is going to adjust the pressure in his garage, and that the garage is attached to his house, but unheated, AND assuming that even colder weather is on the way (Iām talking subzero F), Iād recommend using 5 psi over whatever the tire placard says - which everyone think is 33 psi. So 38 psi. That way when he gets out in the cold, he will be sure to have enough pressure - plus allows for leakage over time until he next checks his pressures.
The good news is he has a monitor on the dash. With that information, he can monitor how well he is doing relative to the pressure specified by the vehicle manufacturer.
The bad news is that he didnāt look at the vehicle tire placard begore posting his question - which makes me think the only thing he cares about is the alert for low pressure he is getting.
So thatās my recommendation - which I donāt expect the OP to follow.
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And, since that alert typically doesnāt show up until a tire is ~25% below the mfrās recommended psi, the OP has apparently been driving with seriously under-inflated tires.
In case the OP isnāt aware of it, driving for extended periods of time on seriously under-inflated tires can damage the tireās internal construction in the sidewall area. That can lead to a blowout at high speedāwith no warning.
Or, here is a crazy thought, just drive down to your closest tire shop once a month and very nicely ask them if they would please check and adjust your air pressure for you, then be nice and give them a tipā¦ $10 to $20 cash depending on your demography is always niceā¦
Discount tire offers free tire pressure checks and adjustments to anyone, not just the folks who bought their tires.
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Capri:
You not only scored a home run with this observation - you knocked the ball out of the stadium!
I donāt know if I said this before, and if I did, it got a lot of people on my case and angry with me about it, but:
Iāve visited dozens of car forums, and perhaps thousands of threads repeating the same question -
āWhat is the correct tire pressure for my Toyota so-n-so, my Chevy whatās-it, or my Mercedes how-you-call itā could have been avoided if people were taught better to look for a sticker containing the information somewhere on their vehicle:
-A door frame
-Glove compt. lid
-Fuel filler access lid
-Trunk lid (old days!)
I didnāt know about the tire inflation and load placard until after 13 years of driving, when I was 30 years old. But the point is I learned.
What would it take to make people aware of this readily available info, and to not look at the tire sidewall for inflation values?
Nothing like taking a simple question and making an engineering class out of it.
Set the recommended pressure on cold tires either in th3 morning or night when the car has not been driven. In this case 33 and 35. Monitor and if it is going to be super cold, you may want to adjust up a little. In my case, I set st 30 but dince it turned cold they are ringing at 28. I may adjust a little if I feel like it.
Geeze guys, really?
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The system I described in my only post here is simpler.
If you check pressure cold ( then temp of gascompound in and out tire the same) note the ambiƫnt temperature.
Then calculate by head, using the list I gave, what it would be at 70 degrF,( can also give a list for degrC), then compate that whith what you determined needed, and if less then 1 psi difference , leave it that way.
Saves you maniacally changing pressure every time.
And main goal , not overheating tire-material is served well.
The recomended pressure is not always the proper pressure.
If you see recomended of 35,36,41 or 42 psi, wich is reference-pressure of P-tire SL or XL, be suspicius.
Can be a not calculated vallue for GAWR and max technical carspeed, and normal use axleloads are lower, wich yustifies an even lower pressure.
That practice has drawn strong criticism from armchair quarterbacks over the years. One person in particular feels that the tire inflation placard is the only valid pressure value that can be used.
It is impractical to send customers out with tires filled to the exact value shown on the tire placard, they will return after two weeks with a low tire pressure complaint. Those who ignore the low pressure might return for service 6 months later, with tires 8 psi under inflated.
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I guess I separate what you have found appropriate for installing new tires (youāre obviously doing it right) to what most folks need to worry about day to day. Some folks have a hard enough time keeping the tires pressures to spec, I donāt think they need to worry about pressure corrections for garage vs. outdoor temps. If they do find their TPMS going off, add 5 psi.
Purely out of curiosity, where did that 35psi in the rears come from?
Two tire pressure sites I consulted all say 33 and 33 for the orig. posterās model year RDX.
I guess weāll have to wait until someone posts a photo of their door frame placardā¦!
Straight out of the owners manual. A paper manual not electronic.
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Then I wonder how difficult it can be for the maintainers of tirepressure . org and similar sites to obtain accurate cold pressure info for the many vehicles they provide it for.
I only care about my own cars and refer to the paper manuals. For the lawn mower and snow blower in look at the tire. For theb other utility tires like wheel barrow, log cart etc, I just feel the tire. We wouldnāt make good neighbors.
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