Tire pressure issue?

I know there are a ton of threads about tire pressure but none seem to answer my question/problem.....
So I have an 18 TRD OR with stock wheels. Label for tire pressure in door says 30 psi cold. They were 29-31 all winter. now that it is warmer they are running 38-42. I let some air out friday down to 34 after I had been driving it. Just got home after driving 30 miles and when I checked them they are at 38. WTF. suggestions?
(other than chalk test)
(also I am in mass so the weather has changed quite a bit since winter cold.)

 

Measure when cold first thing in the morning adjust accordingly

 

so drop it to 30 in the morning? I dont go out till after 9 and it was already 60 out by then. When I lowered it friday it was 55 out when I brought it to 34. But that means I ran my 30 miles today at 38 and it seems stiffer than did in winter. Guess what my real question is if I drop to 30 and run it and it runs say 34 while driving am i doing my ride or tires justice?

 

google is wonderful

https://www.discounttiredirect.com/learn/air-pressure-temperature-flux

typically I see ~34/35psi in the morning ~50ish degrees the up to 42psi in the afternoon ~90ish degrees. It doesn't have to be "perfect". Drive it and enjoy it.

 

I guess my only concern was tire wear if they build up to 40+ but didnt want to drop too much below 30 just to cut down on psi build up on drive.

 

This is easy measure when tire is cold. Check monthly done

 

Go with Nitrogen if it bugs you.
http://www.nitrofill.com/nitrogen-filled-tires-faqs.aspx


"you will find the tire pressure to be more consistent, even during dramatic temperature changes."

 

I think you are overthinking this a bit. Like eldedo said your tire pressure doesn’t have to be perfect. Personally I wouldn’t run any lower than 35psi for on road use with stock tires. They will heat up some, but that’s normal. If you still are concerned then do the chalk test.

 

Tire pressure fluctuates with temperature. Usually about one psi per 10-11 degrees F. So, If you checked in the morning at 40 degrees F and read 30 psi, then in the afternoon at 70 degrees your tires would be 33 psi. Remember, that is the vehicle sitting with no driving. In addition to the ambient temp giving you a three degree delta, your driving (unloaded) is going to add another 2-3 degrees because rolling resistance = friction = temperature rise.

So, to recap, you can leave your house in the morning with your tires at 30 psi and return to your house that evening with your tires at 36 psi, without ever adding air.

What was the question again?

 

HAHAHA
I get it. Thank you all. I just didnt want it to get too high and wear the tires being only 2 months old.

THANKS AGAIN to all that participated.

 

This is simple.

 

I run about 35 PSI when cold and do not worry about the PSI when the tires warm up. I was actually waiting for my stock Toyo tires to wear out so I can buy some better tires. So far I have 28,000 miles on them with a good amount of tread left. Can't complain about that.

 

I run mine at 30 cold all year - that period in the spring when temps are pivoting I let them run high for a bit so I'm not airing every other day but once the warmer temps set in as they have for us now I make sure to air down to 30 cold such that hot they won't generally get above 32-33 which is about the normal variation for heat expansion driving.

I love the way the stock tires ride @ 30 cold / 32-33 warm. Nice and soft but still very responsive and I've done the chalk test and Toyota knew what they were talking about when they put 30 psi on the door. Much higher and (on my truck) it's uneven wear

 

We were in the mountains last July. It was 90 back home and air pressure was fine when we left. It got down to 40 degrees over night and when I started the truck in the am, the low pressure warning came on. By the time we got back home, it was off. Sometimes it happens quicker. I remember years ago we were in gettysburg PA in the summer in our car. We stopped and hung out for a bit on Culp's hill and the air pressure was low and alarm was going off by the time we left. That spooked us a bit just because it was Gettysburg on Culp's hill and the whole damn place is reportedly haunted. And it was dark with a fog rolling in.

I usually inflate have to re-inflate in the winter as it gets real cold just to get back up to 30. When it starts to warm up in April, pressures are up to 35-38 and I have to let some air out. Sounds about fine. Nice to have a protable viaair for those instances to adjust air. plus its nice airing back up after trails.

 

The temperature/pressure change is already explained.
So in winter your 29/31 psi, becomes higher in summer.
Then if you lower the pressure at summer to 29/31 you do it wrong.
In summer the tires need the higher pressures to give lesser deflection so lesser heatproduction.
This because then cooling down of tire is also less because of the lesser temperature differences between rubber and in and outside air . Then the rubber still wont reach a temperature at wich it hardens ereversibly and every new bending by deflection tears these damaged rubber parts a bit further until after a few years a blowout and accident and the missery that goes with it.

When you lowered your pressure , you give tires more deflection so more heatproduction so temp in tire rises more %.
From cold to warm when driving constant 55m/h will rise the pressure about 10%.
Cold is when inside tire temp= outside tire temp, that simple.
Advice is given for 18/20 degr C , 65/68 degr F, and the within a range of outside temp, the warming up/cooling down story stays in balance so rubber wont reach a critical temp.

Will give a picture I made with Excell about the pressure /temp relation, in wich you see that the rule of tumb given , only goes within a sertain range of pressure .

Greatings from a "Pigheaded Dutch Selfdeclared Tirepressure-Specialist"
Peter

 

When I look at your Avatar , its a semi-truck with large tires.
You probably have chanched the P-tires to LT -tires and those need a higher pressure for the same load on them.
EDIT: Reading back I see you have stock tires, so then advice should be alright.
But do you know for shure, check it and compare tiredata with tires given on same plate as the pressure -advices.

I am able to calculate a save pressure for you if you give next.

From car: Best seperate weighed wheelloads in the loading you use the car, so with all the persons and load in it.
Second best is weighing axle loads, but I think we have to do with Empty weight, GAWR's ( gross axle weight ratings), GVWR ( V for Vehicle) , and the way you load it, so what and about where. GA/V WR can be found on the same plate as the pressure advices.
Then the maximum speed you wont go over for even a minute .

From tires 3 things, and mostly can be read from sidewall( check if all the tires are the same).
1. Maximum load or loadindex
2. Kind of tire to determine the pressure for wich the maxload is calculated up to 160km/99m/h mostly.
varies from P-tire ( P in front of sises) in Standard load or XL/reinforced/Extraload, C-load/LRC/6PR,D-load/LRD/8PR, E-load/LRE/10PR.
On LT tires the pressure behind AT I need, and is called in the official formula reference pressure, and for P-tires is not the maximum cold pressure given on sidewall.
3. Speedcode , a letter mostly above Q ( 160km/99m/h) , R( 170km/106m?/H, S,T,H,V,W,Y), But some LT have N speedrated for max 140km/86m/h, but max speed of tire must be the same or more then maximum technical car speed.

Have been playing with your pressure risings in the list I gave and saw next
In winter you had rounded 30 psi all around( 29/31) cold pressure.
Assume 29 to be measured at 32 degrF( freesing point) and 31 at 55degr F . then it will be at advice pressure temp of 65 degr F 32 psi.
Then it has risen to warm pressure to 38/42 wich is then inside tire temp of 130 to 180 degr F. I concluded in time that 140 degr is the max of temp in tire , then rubber wont yust not reach its temp at wich it hardens ireversible.
Now lowering this warm pressure from average 40 psi at 150+ degrF to 34 psi at 150+, it will become cold at 65 degrF. interpolated it as 27.5 psi, wich is 2.5 psi lower then advice.
This gives about 20% more deflection of tire so 20% more heatproduction ( if that is a lineair relation) , pressure rose still to 38 , and looking in the row of 28psi at 65 degr it means an inside tire temp of 190+ degr F.
And the temp in tire is related to the hottest part of rubber, and is the thing what is important for savety of tires.

This all makes me suspect you have those probably even E-load tires with 80 psi for wich maxload is calculated, and your advices on car ar for OEM tires of somewhere between Standardload P-tire to C-load LT.
Then my calculation will come to a higher cold pressure wich rises then only a good 10% in pressure so inside tire temp about 115 degr when driving about 55m/h.

Driving faster means more cicles a second( 55m/h about 10cycles a second). so more heatproduction a second.
for higher speed you then need higher pressure to give tire lesser deflection so lesser heatproduction a cycle, so heatproduction a second stays the same.

 

yes they are all the same from factory.
1 person in the truck and no load in bed.
your explanation makes it all harder to understand.

Im good