RST tire pressure?

Philipgonzales3 · August 21, 2020

Picked up a 2020 6.2L RST Z71 All Star, Leather, Sunroof, etc... on Monday. Noticed the PSI in the app was higher than the door sticker. Thought the ride was going to be bouncy as my LT would bounce more when I had over 35 PSI. Drove fine on the 500 mile trip home. Should I correct the PSI or just send it?

SilveradoRST · August 21, 2020

Try checking the PSI on the app or DIC first thing in the morning after it's been sitting there overnight. Tire pressure will rise as you drive it. To find the true pressure, it has to be checked when the tires have cooled down.

Edited August 21, 2020 by SilveradoRST

Philipgonzales3 · August 21, 2020

4 hours ago, SilveradoRST said:

Try checking the PSI on the app or DIC first thing in the morning after it's been sitting there overnight. Tire pressure will rise as you drive it. To find the true pressure, it has to be checked when the tires have cooled down.

Thanks, I should have mentioned this is the cold PSI. Truck had been sitting for over 24 hours. Checked again just right now (truck hasn't been driven and it's 5:30 AM) I also made sure to refresh the app so it would pull the current values.

econometrics · August 21, 2020

I have the same truck (minus the 6.2L)... same wheels & tires. I run my tires at 32 front and back. I never tow or put anything in the rear, so I don't need the "extra" PSI to 35 on the rears.

So, stick with your door sticker #s and not the app.

Cpl_Punishment · August 21, 2020

If it rides fine, I would consider leaving it. The higher pressure will give you better fuel economy but it could also cause uneven wear on your tires.

Grumpy Bear · August 21, 2020

4 hours ago, Philipgonzales3 said:

Thanks, I should have mentioned this is the cold PSI. Truck had been sitting for over 24 hours. Checked again just right now (truck hasn't been driven and it's 5:30 AM) I also made sure to refresh the app so it would pull the current values.

They remember the last key cycle. When you start the truck again it will take a few moments for the PCM to update all PID's.

Okay that said tire pressured is set by the manufacture for a specific contact patch profile, both static and dynamic, to work in unison with the alignment specs and parts selection to maximize it's efficiency. Latitudes are discussed in your manual. Note that your sticker has different front and back pressures? There's a reason for that.

Philipgonzales3 · August 24, 2020

On 8/21/2020 at 10:33 AM, Grumpy Bear said:

They remember the last key cycle. When you start the truck again it will take a few moments for the PCM to update all PID's.

Okay that said tire pressured is set by the manufacture for a specific contact patch profile, both static and dynamic, to work in unison with the alignment specs and parts selection to maximize it's efficiency. Latitudes are discussed in your manual. Note that your sticker has different front and back pressures? There's a reason for that.

I set the cold PSI to the door sticker. Both me and my fiancee agree that the ride is a little bit more bouncy now. Does this seem right or is that in our heads? lol Felt like riding on a cloud when the were set higher. Debating on leaving them to factory setting or airing them up a bit more. What do you think? You think as long as I keep a 3 PSI difference it would be OK to raise the pressure up a bit?

Grumpy Bear · August 24, 2020

56 minutes ago, Philipgonzales3 said:

I set the cold PSI to the door sticker. Both me and my fiancee agree that the ride is a little bit more bouncy now. Does this seem right or is that in our heads? lol Felt like riding on a cloud when the were set higher. Debating on leaving them to factory setting or airing them up a bit more. What do you think? You think as long as I keep a 3 PSI difference it would be OK to raise the pressure up a bit?

Not in your heads. Tire is an un-dampened air spring. Your powers of observation remain in tact. As pressure increases that springs frequency increases and it's amplitude decreases for a given change in load rate.

The manufacture sets a pressure, as I noted before, to produce and conditions required to obtain a designed effect and effectiveness of the entire package. Tire pressure for example influences the tires heat which influences grip and life. It has some effect on deflection in a turn and so on. These designs favor safety over comfort or utility.

So the question becomes, "Do I think 3 psi detracts from safety"? Yes. Is there another answer I could rationally defend in court? No...

Now that said. Even tire manufactures recommend an addition 1 psi for sustained service over 100 mph

Many vendors recommend and additional 3 psi in the winter.

Your book may recommend some adjustment for load.

These all note that there are exceptions to that sticker.

Anything related to safety has a safety margin. Actually most things related to engineering

Tire pressure is highly related to service life.

I just safely retired a set of 60,000 mile tires at 125,363 miles. The details matter. The question then comes back to you...

Do you drive and maintain in a way that would provide an extra measure of safety about the design that would allow you to take some of that back? My friend I can not answer that for you.

Let me provide a quick example. Let's say at the factory conditions a panic stop from the 70 mph speed limit would stop that truck in say 160 feet. Lets conjecture that a 3 psi increase lengthens that stop 10 feet. How much slower do you have to drive to stop that truck now in 160 feet. Understand?

Philipgonzales3 · August 24, 2020

20 minutes ago, Grumpy Bear said:

Not in your heads. Tire is an un-dampened air spring. Your powers of observation remain in tact. As pressure increases that springs frequency increases and it's amplitude decreases for a given change in load rate.

The manufacture sets a pressure, as I noted before, to produce and conditions required to obtain a designed effect and effectiveness of the entire package. Tire pressure for example influences the tires heat which influences grip and life. It has some effect on deflection in a turn and so on. These designs favor safety over comfort or utility.

So the question becomes, "Do I think 3 psi detracts from safety"? Yes. Is there another answer I could rationally defend in court? No...

Now that said. Even tire manufactures recommend an addition 1 psi for sustained service over 100 mph

Many vendors recommend and additional 3 psi in the winter.

Your book may recommend some adjustment for load.

These all note that there are exceptions to that sticker.

Anything related to safety has a safety margin. Actually most things related to engineering

Tire pressure is highly related to service life.

I just safely retired a set of 60,000 mile tires at 125,363 miles. The details matter. The question then comes back to you...

Do you drive and maintain in a way that would provide an extra measure of safety about the design that would allow you to take some of that back? My friend I can not answer that for you.

Let me provide a quick example. Let's say at the factory conditions a panic stop from the 70 mph speed limit would stop that truck in say 160 feet. Lets conjecture that a 3 psi increase lengthens that stop 10 feet. How much slower do you have to drive to stop that truck now in 160 feet. Understand?

Yes, makes perfect sense. I will just run the factory PSI, as you mentioned there is a reason for the values on the sticker in the first place. I may play around with adding a couple of PSI over, but I understand I do so at my own risk. I employ defensive driving techniques every time I hit the road. I leave plenty of space between the vehicle in front of me (and behind me to the extent I can control) and always try to drive to the conditions of the road. I highly doubt that a few PSI would be the determining factor in an accident, at least not the sole factor. So I think I'm going to stick as close to the sticker as I can while trying to bump it up a couple PSI to see if the comfort increases any, if not I'll drop it back down. That is if I ever feel like breaking out the compressor to air up the tires. May put it off for a while lol.

redwngr · August 25, 2020

Door sticker is recommended pressures for the tire size it was born with, and when the truck is a max load.

If it's a daily driver, and not running 'loaded' you may be able to improve ride by reducing pressures a little. Especially the rears.

Philipgonzales3 · August 25, 2020

32 minutes ago, redwngr said:

Door sticker is recommended pressures for the tire size it was born with, and when the truck is a max load.

If it's a daily driver, and not running 'loaded' you may be able to improve ride by reducing pressures a little. Especially the rears.

Funny thing is my 2019 LT Z71 came over inflated also by around 10 pounds and it felt super bumpy until I bumped the pressure down to what the door sticker said. Maybe a couple PSI below. My 2020 RST Z71 came about 10 pounds over give or take and it felt like riding on clouds, when I bumped down the pressure to the door sticker numbers it seems a little more bouncy but not as bad as the 2019. I heard they firmed up the shocks on the 2020's vs the 2019's. But not too sure which way is up and which way is down right now lol. May just leave them near what the door sticker says and just keep on trucking! lol

econometrics · August 25, 2020

Any time I take my truck to the dealer, they pump my tires up to 40psi all the way around. I think this is just what they do with every 1500 they service.

So annoying. Read the door sticker, tire dude.

Philipgonzales3 · August 25, 2020

1 hour ago, econometrics said:

Any time I take my truck to the dealer, they pump my tires up to 40psi all the way around. I think this is just what they do with every 1500 they service.

So annoying. Read the door sticker, tire dude.

How do you feel it effects the ride? JW. Or do you make them fix it before you drive off?