what pressure do I pump the 'warm?' tires up to?

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Chooch

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This is no doubt a silly question to some, sorry:
The low tire pressure light came on, so after about 10 miles and 15 minutes of driving, I pulled into the nearby gas station. The tires say Max Pressure 44 psi but the door frame sticker says Cold Tire Pressure 36 psi. I couldn't decide which number to pump them up to so they are still low. How hot will the tires be after 10 minutes of driving back to the station? Do I assume they're still cold and fill to 36 psi, or do I assume they are hot at that point and fill to 44 psi, or do I assume they will be warm and just split the difference and fill to somewhere in between? The gas station air pump is one of those where you set the pressure to a certain number and it stops once it gets there but I don't know what number to pick.
Thanks for any advice.
 
If you drive to the station maybe fill them to 38. If pressures are okay, I had my light turn on for no reason, had to run calibration routine. Check the book.
 
As previously mentioned, 36 psi is the Honda recommended tire pressure on door jamb and manual for cold tires that have not been driven on. The actual pressure fluctuates with the temperature of the tire and air inside it (hot air expands). So Viking 79’s advice to go a little up with 38 on a slightly warm is a good rule of thumb until you can check them cold.
The key understanding is that in a properly inflated tire, you do NOT let out any air after driving friction causes the pressure to increase. This will result in under inflated tires.

BTW, the gas station/stop&rob tire pumps are notoriously inaccurate. Do not trust them. Your best bet is to buy an accurate tire pressure gauge. This means not the spring ones at WallyWorld and maybe not even a bourdon tube gauge at the auto parts store. Spend $30 dollars on a quality electronic strain guage that’s accurate to within 1/2 psi.
$30 for a tire gauge, you cry!!!
Well, you just bought a $35,000 Car with $860 worth of high efficiency tires, so $30 spread over a life time is peanuts and will pay for itself in tire life and fuel economy over the years.
Here is a Longacre Racing guage that is highly accurate and reliable. You can Google it for best price.
If no air pump at home, use gas station pump to over inflate a little and use gauge release button at home with cold tires to set correct pressure.
Your tires will thank you and your wallet will stay fat.
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Thanks all for taking the time to reply and explain. I, too, ordered the gauge on Amazon with $5 off coupon :-) It should arrive on Friday and I will deal with the tire pressures and recalibration process (that seems crazy) then. Thanks for your help!
 
I have a little portable air compressor that I keep in the trunk. It has a digital pressure readout and to use it you just plug it into the cigarette outlet in the car, set it to the pressure you want, turn it on and it automatically shuts off when it reaches the correct pressure. The thing takes up barely any room in the trunk. I bought mine from Lowe's but here is a similar one on Amazon: https://smile.amazon.com/Idefair-Co...9357&sr=8-125&keywords=air+pump+for+car+tires
 
I got one of the Longacre gauges today. Thanks, KentuckyKen for the suggestion.

I'm quite impressed with the convenience of the tubing between the valve and gauge, which makes it much easier to read the gauge without getting on my knees. The rubber bumper surrounding the gauge allows me to put the thing on the ground, when necessary, without fear of damage to the gauge. The display increments of 0.2 psi, and a purported accuracy of 0.8% are adequate for my needs.

I also enjoy the ability to bleed off excess pressure,with the gauge active, but without disturbing the valve seal. I found the new gauge easily makes a clean connection with the valve, with minimal air loss, compared to my old Accutire gauge, which I had to fight to get a good seal, resulting in air loss with each reading.

I have somehow misplaced my old 12V air pump, so I used a foot pump to bring them all up to exactly 36 psi. Afterward, it dawned on me that Honda included a 12V tire pump for the repair of leaking tires. It has a setting which is supposedly just air, so I wonder about the wisdom of possibly using that pump for touch-up pressure adjustments, avoiding switching it over to the bottle/repair position. I would welcome any words of wisdom on that. It seems like a waste to buy another pump for that purpose. I am thinking that as long as I have never used the bottled stuff, it might be safe.
 
Since I got a Longacre S3006 gauge, and especially since I picked up a nail puncture on one tire early last month, I've been checking my cold tire pressures pretty often, and I'm seeing a pattern of very slow pressure loss exactly the same on all four of the tires. I saw a drop of 1.0 psi after 22 days, and another 0.8 psi on the following 16 days. By rough calculation, it looks like all of the tires are losing about 0.05 psi per day, or about 1 pound every 20 days. Each measurement was done early in the day, in the garage, with no driving since the prior early evening, so the tires are cold. The garage temp has been between 80-83 degrees during each measurement.

With all of them having the same exact slow air loss, I'm not concerned that I have a puncture/leak on one of them, but I wonder if that is just typical air loss, and nothing to be really concerned about. I've never tracked air pressure so frequently, or carefully before. I have scheduled my TickTick app to remind me to check tire pressures at least once a month, and tweak up as necessary.
 
There is no valid calculation for how much more than cold tire pressure to add to driven on warm tires that I know of. There’s just too many variables. So you’re forced to always check and add pressure when tires have not been driven on and are cold. If tires are sealed well to rims, have no punctures or defects, and the valves are not leaking, then you only need to check them once a month.
It’s analogous to checking your stocks every day; the daily fluctuations are not meaningful and will drive you crazy. Just check tires cold once a month and if necessary add to keep them at 36 psi.
Congrats on your Longacre purchase. I think it’s the best gauge out there. Keeping the tires properly inflated will save tires, kW, and gas.
 
Carro con enchufe said:
After seeing another thread about TPMS I bought this cigarette lighter powered TPMS, so I can see tire pressure in real time. It ranges from 35-38 depending if it’s cold or been running.
https://www.amazon.com/Pressure-Monitoring-Real-time-Cigarette-CL-203/dp/B01LA90R6Q
Click to expand...

I like the simple and non-invasive approach of using the cigarette lighter/DC Power Plug for the TPMS indicator, rather than one on top of the dash, but with the positioning of that plug under the gearshift island on the Clarity, I wonder if you are able to actually read it without having to contort yourself?
 
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vicw said:
I like the simple and non-invasive approach of using the cigarette lighter/DC Power Plug for the TPMS indicator, rather than one on top of the dash, but with the positioning of that plug under the gearshift island on the Clarity, I wonder if you are able to actually read it without having to contort yourself?
Click to expand...
You can’t read it while driving but you can at start up or red lights. It will beep if pressure goes down, though I’m not sure of the threshold.
 
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