Tire Pressure Question for Tire Experts

[DanFelix]

I live in a SoCal desert where there is a 30 deg swing in temperature from sunrise to sunset. If I set my tires to the recommended 36 psi “cold tire” setting, then half the day they run at 40 to 41 psi.

Of the two evils, which is worse? Running the tire under or over pressure? Is the over-pressure error a meaningful problem?

TIA for answering this hot air question.

-Dan

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[Opus]

It will depend on the kind of drive you do. If it's a lot of highway I would err on the side of higher pressure. Plus, you'll be less likely to get the warning light on the dash if your pressure is too low.

 

[Heimkehr]

Of the two evils, which is worse? Running the tire under or over pressure?

I'd default to a bit of overpressure. An underinflated tire can cause all sorts of voodoo, as Ford discovered some years ago with their Explorers.

 

[Chocolate Thunder]

Tire pressures are stated as cold pressure. It’s normal and expected for them to run a few pounds higher when in use. Also, the recommended pressure is just that - a recommendation from the manufacturer based on general use and prioritizing fuel efficiency and tread wear over comfort, traction, and handling.

You can tinker around with pressure to find what fits your driving and circumstances best.

 

[gsbrockman]

Tire pressures are stated as cold pressure. It’s normal and expected for them to run a few pounds higher when in use.

This......
Cold pressures are the baseline when setting tire pressure.

 

[Upnarms]

I make frequent trips from the desert to the pines, going from 1200' asl to 7000' asl. Temps will be 100 when I start and in the 50s or 60s where I end up. I usually start cold pressure in the 33-34 range and end up in the 40-41 range up top. Even driving in the desert, the morning psi will be in the low 30s and with the heat and driving will go up to the high 30s. A swing of 5-6 psi is pretty common.

I agree if you do a lot of highway driving, err on higher. Tires heat up and break down faster at high speeds and low psi

 

[KCSgtMaj]

The over pressure is worked into the design of the tire. Which is why you set the tire pressure cold or ambient temperature.

 

[The Last Cowboy]

You can try 32 PSI cold, which should get you to about 37-38 when up to temp. You don't want them less than 30 PSI cold. I believe once they hit 28-29 PSI cold, the low tire pressure light will come one. It helps to have a compressor at home if you are doing this. Everyone should have one.

 

[Kierrr]

Mine are at 33PSI cold and I have the tire pressure warning light.

2023 High Tide

 

[JT1]

Mine are at 33PSI cold and I have the tire pressure warning light.

2023 High Tide

Air them up to 37 and start the jeep. The TPMS light should clear.
You can then drop them to whatever you want. Anecdotally, another member on here has a 23 and says 33 is the new low pressure trigger, not 30.

Invest in a tazer or jscan and you can adjust that.

 

[The Last Cowboy]

Mine light at 29 I belive. And yeah, you have to fill to 37 to turn the light off. Then you can adjust down after that.

 

[pnut]

I live in a SoCal desert where there is a 30 deg swing in temperature from sunrise to sunset. If I set my tires to the recommended 36 psi “cold tire” setting, then half the day they run at 40 to 41 psi.

Of the two evils, which is worse? Running the tire under or over pressure? Is the over-pressure error a meaningful problem?

TIA for answering this hot air question.

-Dan

I would always default to the manufacturers recommendation (assuming running stock size tire). Which is the pressure listed on the sticker in the driver door opening, when measured at cold (meaning not in the sun, not after driving, but just sitting). I truly believe in the engineer's work that this is the best starting point for all the following swings in temps. This assumes street driving not offroad.

 

[Kierrr]

I would always default to the manufacturers recommendation (assuming running stock size tire). Which is the pressure listed on the sticker in the driver door opening, when measured at cold (meaning not in the sun, not after driving, but just sitting). I truly believe in the engineer's work that this is the best starting point for all the following swings in temps. This assumes street driving not offroad.

Except, in highway driving my car drives significantly better (smother, less bouncy, more in control) at 35 PSI than it does at at 37 PSI. Significantly better.

I'm still trying to decide if I prefer 33 PSI to 35 PSI. (Not sure I do tbh.)

 

[Flip]

I know this isn't for everyone and I'll probably take a browbeating for this but I disabled that confounded whatchamacallit PMS - TPMS sensor. I grew up without it, I don't like it, I don't want it, IMO they're a pita. When I air down on the trail, no blinking light, I run my tires around 32-33 psi. I check my tire pressure twice a month. Old school dude?

Best of luck

 

[richk225]

I know this isn't for everyone and I'll probably take a browbeating for this but I disabled that confounded whatchamacallit PMS - TPMS sensor. I grew up without it, I don't like it, I don't want it, IMO they're a pita. When I air down on the trail, no blinking light, I run my tires around 32-33 psi. I check my tire pressure twice a month. Old school dude?

Best of luck

I like the way you think. There are so may forum members that are running their tires at much lower pressures like f28/26r 30/30 and all over the place. I would do a chalk test just to see how much of your tire is making contact with the ground. I had my XR 392 serviced and they filled the tired up to 37 psi and when I did the chalk test there was roughly 6 inches of the center of the tire making contact with the driveway, I did the chalk test the next day before it was driven so that would be cold tire pressure, then I drove around and the dash read 45psi all around and when I chalk tested the tire at 47psi there was barely 5 inches of tire making contact

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