Automotive

Another tire pressure thread (summer time only)

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  • Jun 9th, 2016 9:32 am
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Deal Fanatic
Jun 22, 2004
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Another tire pressure thread (summer time only)

A few days ago I checked my tire pressure when my engine was cold. It was somewhat low and around 2 PSI below normal. I didn't have time to add air.

Just today, I checked my pressure after driving a while and temps were in the high to mid 20s. My tire pressure was way above the maximum recommended PSI on the door jam but below the maximum threshold for the tire.

I was thinking if I should bump up the pressure by 2 PSI or should one lower their tire pressure to the recommended PSI in the summer after driving for a while?
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Oct 16, 2007
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Set your cold tire pressure to the recommendation on the door jam.
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Dec 27, 2006
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Cornwall PE
I think you think too much.
Anyway check it once a week or so and always go by what it says on the door jamb, and stop worrying how much difference 5 degrees this or that will make. Then have a beer and relax.
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Aug 22, 2011
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Hey, good to hear you're checking regularly.
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Sep 3, 2005
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Vaughan
OP, its normal for the tires psi to go up after driving. I usually set/check pressure after i let the car sit over night. I've check pressure after letting the car sit for 2 hours before, and it was higher than it was supposed to be. I would recommend letting the car sit for a lomg period of time before you do set/check psi.
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Jul 26, 2007
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And what was the recommended psi on your door jam say?
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Oct 13, 2009
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Look at door jamb, set pressure to that number when car is cold.
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Deal Expert
Mar 25, 2005
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Hot tire pressure does not mean much, always set while cold.
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Jul 22, 2014
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Ottawa, ON
This reminds me, time for my annual tire pressure check.
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Aug 15, 2015
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Kasakato wrote: Hot tire pressure does not mean much, always set while cold.
Considering most of the driving on long trips is done on that hot pressure, I would have to disagree with you. I don't care if my tire sits in my driveway at correct pressure as the wear will happen when moving. I also use the tire specs as the inside door jamb usually is related to the tires that were originally supplied by manufacturer and not the specific tires you are using .
If you put low profile tires and big rims, God help you if you use the door jamb pressure guide.
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Sep 9, 2012
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Pavel wrote: A few days ago I checked my tire pressure when my engine was cold. It was somewhat low and around 2 PSI below normal. I didn't have time to add air.

Just today, I checked my pressure after driving a while and temps were in the high to mid 20s. My tire pressure was way above the maximum recommended PSI on the door jam but below the maximum threshold for the tire.

I was thinking if I should bump up the pressure by 2 PSI or should one lower their tire pressure to the recommended PSI in the summer after driving for a while?
Set tire pressure when the tires are cold not when the engine is cold. Setting when the tires are cold just means that they haven't heated up from driving. Best bet is to check the pressure in the morning after the car has sat overnight. Once you know the cold reading, compare to the door jamb or owners manual.
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Oct 5, 2008
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iddqd85 wrote: this reminds me, time for my annual tire pressure check.
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Feb 16, 2016
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Casselman, Ontario
Interesting thread. I was wondering as well. On my ML350 they say 48 psi at the door jamb...I was like wtf? I've never seen tire pressure that high...all of my previous cars were in the 35 range. I would be worried at 48 psi...I'll have to ask on the MB forums.
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Jul 22, 2014
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Ottawa, ON
dilligafeh wrote: Considering most of the driving on long trips is done on that hot pressure, I would have to disagree with you. I don't care if my tire sits in my driveway at correct pressure as the wear will happen when moving. I also use the tire specs as the inside door jamb usually is related to the tires that were originally supplied by manufacturer and not the specific tires you are using .
If you put low profile tires and big rims, God help you if you use the door jamb pressure guide.
I'm pretty sure your vehicle manufacturer thought about that before coming up with the pressure specs. I do agree with you about low profile tires, they need to be inflated higher.
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Aug 15, 2015
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iddqd85 wrote: I'm pretty sure your vehicle manufacturer thought about that before coming up with the pressure specs. I do agree with you about low profile tires, they need to be inflated higher.
Just as they thought of the ignition switches at GM or emissions at WV, airbags anyone ? Manufacturers do things based on what maximizes profits not what yields the customer the best experience and value. I have always experienced feathering with manufacturer specs so I inflate my tires according to tire specs and make sure they're where I want them when driving even though it's only a couple of psi difference that won't hurt anything other than fuel when low.
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Feb 10, 2015
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Tire pressure specs on the door jamb don't mean anything. The manufacturer has those set for comfort.

I always set my tires a couple pounds below the max number on the sidewall. This will give a bit rougher ride but better overall performance.
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Mar 25, 2005
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dilligafeh wrote: Considering most of the driving on long trips is done on that hot pressure, I would have to disagree with you. I don't care if my tire sits in my driveway at correct pressure as the wear will happen when moving. I also use the tire specs as the inside door jamb usually is related to the tires that were originally supplied by manufacturer and not the specific tires you are using .
If you put low profile tires and big rims, God help you if you use the door jamb pressure guide.
You are aware the manafacture specified a cold tire spec correct? The spec provided accounts for the heat generated when actually moving. The hot tire pressure means nothing when setting pressures.
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Aug 15, 2015
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Kasakato wrote: You are aware the manafacture specified a cold tire spec correct? The spec provided accounts for the heat generated when actually moving. The hot tire pressure means nothing when setting pressures.
So what ? They specify many things that are not necessarily the best performance or for the longevity of the vehicle or tire. You're free to follow their rules off a cliff if you wish, I will have my reserves and use my best judgement however so no need to continue this discussion.
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Sep 22, 2009
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DanTh3Man wrote: Tire pressure specs on the door jamb don't mean anything. The manufacturer has those set for comfort.

I always set my tires a couple pounds below the max number on the sidewall. This will give a bit rougher ride but better overall performance.
When you say performance, can you be more specific? Were you talking about fuel economy? Or braking/acceleration.

If you have been to the tracks, slightly lower pressure = more traction

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