Warm tire psi - adding
Thread Starter
Melting Slicks
Joined: Jul 2011
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From: Maryland
St. Jude Donor '13
Warm tire psi - adding
Quick question. I'm on my iPhone so bear with me. I was driving my Corvette and I check the tire pressure and I noticed that it was 27 in front and 28 in the rears. So went to the gas station to add some air and when I got there the tires were already warm and it was 30 in the front and 31 in rears. So I added air until it read 35 evenly across all of them taking note that this was with warm tires. Is this okay or is this overinflated? I assumed it would be about 30-31 when it cools, maybe 32 tops.
I haven't had a chance to add when it was cold though. Schedule and air pump at home not working at the moment so it's always warm by the time I get anywhere
I haven't had a chance to add when it was cold though. Schedule and air pump at home not working at the moment so it's always warm by the time I get anywhere
Thread Starter
Melting Slicks
Joined: Jul 2011
Posts: 2,198
Likes: 0
From: Maryland
St. Jude Donor '13
Awesome, thanks y'all
It's actually 34 on the left two tires and 35 on the right two tires now, but with the air checker they're close enough.
I'm guessing it'll be ~31 (give or take 0.5-1) when they're cold. As long as they're between 30-32, I probably won't let any air out since if it is 32 it would be barely 32.
I just wanted to double check since I haven't actually added air to warm tires before and for some reason my home pump (with a much better air checker) is not working
Alright, thanks again!
It's actually 34 on the left two tires and 35 on the right two tires now, but with the air checker they're close enough.
I'm guessing it'll be ~31 (give or take 0.5-1) when they're cold. As long as they're between 30-32, I probably won't let any air out since if it is 32 it would be barely 32.
I just wanted to double check since I haven't actually added air to warm tires before and for some reason my home pump (with a much better air checker) is not working
Alright, thanks again!
Team Owner
Joined: Mar 2008
Posts: 21,502
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From: Southern Utah
If you can't inflate them when cold, for whatever reason, then it's best to purposely overinflate them when you are on the way home, let them cool overnight and then when they are cold, let air out until they get to the right pressure.
Team Owner
Joined: Jun 2005
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From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
correct. I used to live about 2 miles from an air pump. I'd ck the pressure before I left, and add what I wanted (say 3 lbs of air) to whatever was the "heated" tire pressure. next morning I'd ck it and deflate as needed. usually, it was very close to what I'd wanted to have as the final, new pressure.
CF Senior Member
Joined: Feb 2006
Posts: 23,313
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From: Tucson Arizona
You're fine for now but check the tires in the morning when they're cold. It depends on many factors but most often you don't heat the tires up all that much driving down the street. Trying to accurately adjust hot tire pressures can be difficult....just having one side of the car parked in the shade can throw you off. FWIW I typically run an extra pound or so in the front tires to help compensate for the car's 51/49 weight distribution ratio. Ideally, I wouldn't run higher pressure in the rear tires.
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Safety Car
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From: Northern VA, USA
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Team Owner
Joined: Sep 1999
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From: Springfield MO
You're fine for now but check the tires in the morning when they're cold. It depends on many factors but most often you don't heat the tires up all that much driving down the street. Trying to accurately adjust hot tire pressures can be difficult....just having one side of the car parked in the shade can throw you off. FWIW I typically run an extra pound or so in the front tires to help compensate for the car's 51/49 weight distribution ratio. Ideally, I wouldn't run higher pressure in the rear tires.
My nose heavy Mercedes (front engine w/supercharger and rear wheel drive) has a Mercedes spec of 28#front/32# rear for the cold air pressure. They spec more air pressure in the rear, not to support more weight in the rear(as the car is lighter in the rear), but to have the car handle correctly. They do say when driving over 100 MPH to add an additional 4# of pressure, to all tires. That info is on the placard located on the car.
Race Director
Joined: Jan 2011
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From: Tonawanda New York
I thought we were talking about street use. I stand by my reply.
Safety Car
Joined: Feb 2011
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From: Arlington VA
Thanks!
Racer
Joined: Aug 2011
Posts: 373
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From: Iron Station, NC
I was about to reply "fill the tires with nitrogen" (a mechanic at the shop suggested that) THEN I thought let me educate myself on this topic before I do that.
According to the attached website tire pressures change 1 psi for every ten degrees change in Fahrenheit.
Same for air or Nitrogen, Nitrogen is used in racing etc.. because of the lack in moisture content which creates a more stable/predictable enviroment.
http://www.tirerack.com/tires/tirete...813&techid=191
According to the attached website tire pressures change 1 psi for every ten degrees change in Fahrenheit.
Same for air or Nitrogen, Nitrogen is used in racing etc.. because of the lack in moisture content which creates a more stable/predictable enviroment.
http://www.tirerack.com/tires/tirete...813&techid=191
Tech Contributor
Joined: Oct 1999
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From: Charlotte, NC (formerly Endicott, NY)
The tires are supposed to be set at 30 cold. If your tire pressure was 27 then you had to add 3 lbs to get to 30. If the warm pressure turned out to be 30 then all you had to do was add 3 lbs to get the warm pressure up to 33. When the tire cooled down to the temp it was at when you took the cold temp the pressure would be at 30. Super position holds.
Bill
Bill
Race Director
Joined: Apr 2007
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From: Toronto, Canada
C7 of the Year - Unmodified Finalist 2021
Quick question. I'm on my iPhone so bear with me. I was driving my Corvette and I check the tire pressure and I noticed that it was 27 in front and 28 in the rears. So went to the gas station to add some air and when I got there the tires were already warm and it was 30 in the front and 31 in rears. So I added air until it read 35 evenly across all of them taking note that this was with warm tires. Is this okay or is this overinflated? I assumed it would be about 30-31 when it cools, maybe 32 tops.
I haven't had a chance to add when it was cold though. Schedule and air pump at home not working at the moment so it's always warm by the time I get anywhere
I haven't had a chance to add when it was cold though. Schedule and air pump at home not working at the moment so it's always warm by the time I get anywhere
Instructor
Joined: Nov 2010
Posts: 216
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From: TN
The tires are supposed to be set at 30 cold. If your tire pressure was 27 then you had to add 3 lbs to get to 30. If the warm pressure turned out to be 30 then all you had to do was add 3 lbs to get the warm pressure up to 33. When the tire cooled down to the temp it was at when you took the cold temp the pressure would be at 30. Super position holds.
Bill
Bill
