Tempory tire pressure increase from driving

[Retired Bob]

I have a 2014 Chevrolet Silverado 1500 2wd Double Cab with

Goodyear Assurance CS TripleTred tires. My recommended cold tire pressure for the Silverado is 35lbs all around. Recently in getting ready to take a trip from SC to GA I inflated the tires to 35lbs early in the morning before the sun was up. Almost as soon as I got on the Interstate the pressure showed 39lbs all around on my info center tire pressure display (shows all 4 tires independently) and by 11am was showing 40lbs all around. I was driving 70mph and the outside temp was approx 65 degrees at 11am. I understand that the temporary hot pressure can be 5 to 6 degrees higher than the recommended cold tire pressure.

 

Was it OK/safe to drive approx 200 miles at 40psi? How much higher could the 'temp hot pressure' safely reach if the outside temp was 85 degrees - would the tires go much higher than the 'hot' 40psi? Could the 'temp hot pressure' ever reach an unsafe tire pressure - say in the summer heat?

[Daly]

You're fine. All tires do that as they heat up, the air inside expands and has no where to go, so the pressure increases. 

[btj_z71]

2 hours ago, Retired Bob said:

I have a 2014 Chevrolet Silverado 1500 2wd Double Cab with

Goodyear Assurance CS TripleTred tires. My recommended cold tire pressure for the Silverado is 35lbs all around. Recently in getting ready to take a trip from SC to GA I inflated the tires to 35lbs early in the morning before the sun was up. Almost as soon as I got on the Interstate the pressure showed 39lbs all around on my info center tire pressure display (shows all 4 tires independently) and by 11am was showing 40lbs all around. I was driving 70mph and the outside temp was approx 65 degrees at 11am. I understand that the temporary hot pressure can be 5 to 6 degrees higher than the recommended cold tire pressure.

 

Was it OK/safe to drive approx 200 miles at 40psi? How much higher could the 'temp hot pressure' safely reach if the outside temp was 85 degrees - would the tires go much higher than the 'hot' 40psi? Could the 'temp hot pressure' ever reach an unsafe tire pressure - say in the summer heat?

Every increase of 10 degrees Fahrenheit equates to an increase of 1 PSI.  So, your tires simply warmed up. 

 

You tires have a letter rating for temperature and traction.  The higher the temp rating, the better they are at getting rid of heat.  So, take that into consideration as well.  The weight each tire is bearing will also affect the tires ability to cool down.  As with most things, there are many variables at play to be considered.  

 

You are not in any place where you need to worry about the tires. 

[KARNUT]

I’m sure most people by now know what to expect when the temperature drops. When the monitors first came out it must have been fun when a cold front came through.


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[Retired Bob]

btj_z71, thanks for the 'reply'. You're correct on there being so many variables. These Goodyear tires have a B Temperature rating (see the meaning below) so I'm OK as far as speed and its effect on temperature. I guess my question was - if the tires were 35psi in the early morning and then rose to 40psi by driving at 70mph with a outside temperature of 65 degrees, how much higher could the tire temp go to if the outside air temp was 85 F instead. Could the tire temp go to, say, 43 psi or higher? Is there some max temp that they might go to, with no heavy load involved. Certainly the temporary hot temp would not go to 50psi would it?  The tires show a Max inflation of 51psi . I suppose with everything considered, the tires would never reach an unsafe driving psi due to temperature. Would not want them to explode (never heard of that happening though).

 

BTW, I got these tires because the original tires were Goodyear Fuelsavers and the tread wear was terrible, so Goodyear offered me a new set of tires provided they were a Goodyear Brand

 

Temperature (Resistance) Grades

The UTQG Temperature Grade indicates the extent to which heat is generated and/or dissipated by a tire. If the tire is unable to dissipate the heat effectively or if the tire is unable to resist the destructive effects of heat buildup, its ability to run at high speeds is reduced. The grade is established by measuring a loaded tire's ability to operate at high speeds without failure by running an inflated test tire against a large diameter high-speed laboratory test wheel.

Temperature Grades	Speeds in mph
A	Over 115
B	Between 100 to 115
C	Between 85 to 100

 

Every tire sold in the United States must be capable of earning a "C" rating which indicates the ability to withstand 85 mph speeds. While there are numerous detail differences, this laboratory test is similar in nature to those used to confirm a tire's speed ratings.

Unfortunately for all of the money spent to test, brand and label the tires sold in the United States, the Uniform Tire Quality Grade Standards have not fully met their original goal of clearly informing consumers about the capabilities of their tires. Maybe it's because tires are so complex and their uses can be so varied, that the grades don't always reflect their actual performance in real world use.

[Grumpy Bear]

There should be stamped on the tire near the rim a maximum inflation pressure value. This is not the set pressure on the door sill but the tires limit. Setting to the suggested number it should never exceed that maximum value hot. That said you have to keep the variables in mind when setting cold pressures. If you are setting them in the AM at 60F and know your trip is going to happen at 4 PM and the temp at that time will be 80F make the mental 2 psi adjustment. If you know your trip will be driven at 80 mph then don't make that compensation. 

 

A tire under inflated runs hot. One over inflated wears out. Neither provide optimum traction. Both are dangerous.   

 

The Bridgestone on my truck are to be set as yours, 35 psi cold. The max stamped on the tire is 41 psi. A rough rule of thumb is a properly inflated P metric tire at a steady air temperature will rise about 10% from cold to hot running. 3 or 4 psi. That gives you a 20 F air temperature cushion. LT and E rated tires don't rise as much. Stiffer sidewalls. You really have to observe and keep track for awhile to know how your tire will respond.  

 

I'm anal about tire care and have 105,000 miles on this set with 5/32 tread left. 

 

Could the temperature get 43 psi or higher? Sure, in a perfect storm. Running on a bad alignment/worn out suspension when over loaded at high speeds on new asphalt on a blister of a day when you set pressures that morning when it was 50 degrees cooler. 

 

Get a good gauge and start monitoring it to find your normal. Take a breath... Remember slowing down will always cool tire. 

 

My two cents. 

[D_Spin]

The tire pressure listed on the door jamb (nobody is inflating to the max listed on the sidewall right?) is the cold pressure. Cold is 32*F or 0*C. For every 10*F above 32*F the pressure will rise 1 PSI. So if you set the pressure to 35 PSI when its 85* outside, you will be low when the temp drops. The Manufactures know the law that Temp and Press are directly related for any gas, including ambient air (tiny adjustments for humidity not withstanding). Thats why they list the pressure on the door with a temp. When I set my tire pressures, I always take in account the ambient temperature.  If I'm hauling something, or towing something, I adjust the pressure accordingly. 

 

So when you set your pressure, figure in the temperature also. 35PSI at 32* = 40PSI at 82*. Its not 35PSI at every temp... Its 35* at 32*F

[HeySkippyDog]

I'm anal about everything and have 105,000 miles on this set with 5/32 tread left. 

Fixed it!

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[Grumpy Bear]

4 hours ago, D_Spin said:

The tire pressure listed on the door jamb (nobody is inflating to the max listed on the sidewall right?) is the cold pressure. Cold is 32*F or 0*C. For every 10*F above 32*F the pressure will rise 1 PSI. So if you set the pressure to 35 PSI when its 85* outside, you will be low when the temp drops. The Manufactures know the law that Temp and Press are directly related for any gas, including ambient air (tiny adjustments for humidity not withstanding). Thats why they list the pressure on the door with a temp. When I set my tire pressures, I always take in account the ambient temperature.  If I'm hauling something, or towing something, I adjust the pressure accordingly. 

 

So when you set your pressure, figure in the temperature also. 35PSI at 32* = 40PSI at 82*. Its not 35PSI at every temp... Its 35* at 32*F

Cold pressure is the pressure before driving and heating up the tires. 

 

 

 

It doesn't have to be this hard. 

[HeySkippyDog]

Bear in mind that your door sticker likely recommends 33 psi for 18"wheels and stock tires.

I think my 2014 with 20s recommended a little higher. I think 36 was on the sticker?maybe somebody can chime in.

EITHER WAY, 35 for either configuration and even for the 17" wheel is a nice happy medium I have stuck to for many years in my trucks with P tires.

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[Eddie 70]

I run cold pressure of 38 in mine. Hardly ever do the pressures get much higher than 40. You are fine, well below the max tire pressure.

[Retired Bob]

So much info on tire pressure is available - some conflicting but most about the same in general.  Most info says to check your tire pressure when cold - before the sun heats up the tire and before driving more than a couple of miles.

 

"Using a gas station air compressor means your tires might be “hot.”  If it is necessary to adjust inflation pressure when tires are “hot”, set their pressure to 4 psi (14 kPa) above the recommended cold inflation pressure. Recheck the inflation pressure when the tires are cold.

After filling your tires, use the gauge to check pressure again. At this point, it’s ok if you overfilled the tires because you can always let some air back out. Never drive on overinflated tires. Overinflation can result in decreased traction, premature wear, and decreased impact absorption."

 

So, to be anal, check your tires in the morning when cold, but if you know the ambient daytime temperature  will be 25F degrees warmer during the times you will be on the road during your trip, you might inflate your tires in the early morning before the trip to maybe 1 or 2 pounds under the recommended cold inflation pressure knowing the sun, ambient daytime temperature (which will be much warmer once the sun comes up) and the heat from driving on the Interstate will increase the tire pressure and this will prevent the tires from becoming over inflated during the trip.  Then check and adjust the tire pressure again after the trip or when you know the ambient daytime pressure will not be as extreme. Or, just do the best you can

 

But, reading the statement in italics above, don't let the driving on the trip cause the tires to become overinflated. Some year soon vehicles will probably have a computer sensor to automatically deflate or inflate the tires while driving so as to maintain the prefect inflation suited for the conditions at all times.

 

[KARNUT]

WOW, lots of worries over tires. I under inflate my tires for ride. Sometimes as much as 5LBs. I’m interested in ride quality. Never a problem with wear. I don’t wear all the way down to the wear beads either. I tell the service dealer not to but air in my tires just rotate. If the light comes on I just add enough to shut it off usually after the first cold snap.


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[YukonXL04]

So let me ask this. What about towing a heavy load? My tires are rated for max weight at the max 51 psi cold. At 35 psi the truck is very squishy and borderline unstable at highway speeds. 

So towing I usually set my pressure around 48 all around. But starting in the north at 35° outside and going south at 75° outside along with the heat from heavy load and highway speeds my tires have gotten up to 54-55psi. Am I supposed to pull over and let air out?

[KARNUT]

So let me ask this. What about towing a heavy load? My tires are rated for max weight at the max 51 psi cold. At 35 psi the truck is very squishy and borderline unstable at highway speeds. 
So towing I usually set my pressure around 48 all around. But starting in the north at 35° outside and going south at 75° outside along with the heat from heavy load and highway speeds my tires have gotten up to 54-55psi. Am I supposed to pull over and let air out?

I did exactly that. From the mid 80s to the mid 2000s. My gooseneck trailer had 8 tires inflated cold to the recommended tire pressure. I traveled hauling my equipment through hot to cold climate and back. I never had a tire issue. I can say that now retired and not jinx myself. I used the best tire at the time with the highest ply and load rating. Michelin tires


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