Hot versus Cold Tire Pressures?
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Intermediate
Joined: Jun 2007
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From: Marion IN
Hot versus Cold Tire Pressures?
Have been running 30# cold tire pressures. After extended Interstate driving periods the pressures will jump up to around 36#. (Driving in the eastern CA and western AZ recently.) This seems too high to me. Not enough miles to see any excessive center wear, but really don't want to. Question is, what is the optimum hot tire pressure recommendation for our cars? I don't think I have ever seen these numbers. I guess you would have to know some things: Goodyear runflats, interstate cruising, and about 70 degrees? Anybody have any experience?
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Have been running 30# cold tire pressures. After extended Interstate driving periods the pressures will jump up to around 36#. (Driving in the eastern CA and western AZ recently.) This seems too high to me. Not enough miles to see any excessive center wear, but really don't want to. Question is, what is the optimum hot tire pressure recommendation for our cars? I don't think I have ever seen these numbers. I guess you would have to know some things: Goodyear runflats, interstate cruising, and about 70 degrees? Anybody have any experience?
35/36 is to hot for runcraps
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Intermediate
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From: Marion IN
Seems there may be a difference of opinion already. I figured. I think (to answer my own question after thinking about it some more) that maybe the only way to answer this question is to run the 30# long enought to establish a wear pattern for my driving and adjust from there. Just hate to let the wear pattern develope because it never seems to go away after that. The knowledge gained is only good on the second set of tires. Those, however, will not be Goodyear runflats. Oh well. Thanks for the replies.
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From: Horncastle Lincolnshire, England
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As a reference I used to set 30 cold in Vegas and get up to 35 hot. I've been setting 29 cold in England during Summer and get about 32 hot at most.
There's definitely a difference in variation when the temperatures are higher so your 36 in the AZ desert makes sense.
If GM recommend 30 cold I'm thinking they expect about 32 hot. To that end, I tend to set a psi or two lower than 30 cold. I've also seen threads that suggest that the Michelin AS ZPs, which I have fitted, tend to wear harder in the center so I'm keen to avoid over inflation.
As the temperatures drop for winter I'll keep an eye on my hot temperatures and may go back to 30 cold. All this effort is probably worth it as the pressures have an impact on both mpg and handling.
There's definitely a difference in variation when the temperatures are higher so your 36 in the AZ desert makes sense.
If GM recommend 30 cold I'm thinking they expect about 32 hot. To that end, I tend to set a psi or two lower than 30 cold. I've also seen threads that suggest that the Michelin AS ZPs, which I have fitted, tend to wear harder in the center so I'm keen to avoid over inflation.
As the temperatures drop for winter I'll keep an eye on my hot temperatures and may go back to 30 cold. All this effort is probably worth it as the pressures have an impact on both mpg and handling.
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From: Horncastle Lincolnshire, England
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Seems there may be a difference of opinion already. I figured. I think (to answer my own question after thinking about it some more) that maybe the only way to answer this question is to run the 30# long enought to establish a wear pattern for my driving and adjust from there. Just hate to let the wear pattern develope because it never seems to go away after that. The knowledge gained is only good on the second set of tires. Those, however, will not be Goodyear runflats. Oh well. Thanks for the replies.
If you want to stay with RFs, the Michelins are great. If you want to switch to non RF, there's a big choice.
The handling and ride noise are massively improved on new rubber.
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For peace of mind, get your alignment checked. Every street tire I've ever run gains ~5lbs of pressure from cold to hot. 25lbs is a little low, 40lbs is a little high. Keep it between there and you'll be fine.
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I try and set mine to where they will read 30 psi hot. That means usually around 28 or so psi cold.
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Hi jaw22w -
This has always been a dynamic of air filled tires.
If you feel the need to have more consistency in your hot/cold pressures, then find a dealership that can inflate your tires with nitrogen.
It costs about $5 a tire here in Peoria.
best regards -
mqqn
This has always been a dynamic of air filled tires.
If you feel the need to have more consistency in your hot/cold pressures, then find a dealership that can inflate your tires with nitrogen.
It costs about $5 a tire here in Peoria.
best regards -
mqqn
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From: Gadsden Alabama
I always figured that the GM engineers knew that tires actually heated up and caused the pressure to increase while driving. I also always figured that they knew the cars were sold in all parts of the country and that some areas were hotter than others. After taking all of this into account, they recommended 30psi COLD as an all around safe pressure setting for the stock GY RF's. Now, having said that, it doesnt mean that if somebody uses a different brand or style of tire or has more extreme driving habits or conditions that the pressure can't be adjusted some to suit the driver or adjust the wear.......
atilla....
atilla....
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GM knows what they're doing when they say 30# COLD, Just as Mercedes knows what they're doing when they say 28# COLD/front & 32# COLD/rear, and +4# COLD for substained driving over 100MPH on my DD.
On the C2's, GM said that the tire pressures should be 24# COLD(after standing 3 hours or less than a mile), 26# HOT(3 miles or more below 40 mph) or 28#(3 miles or more above 40 mph). For sustained high-speed driving, a starting pressure of 36 #'s was recommended.
On the C2's, GM said that the tire pressures should be 24# COLD(after standing 3 hours or less than a mile), 26# HOT(3 miles or more below 40 mph) or 28#(3 miles or more above 40 mph). For sustained high-speed driving, a starting pressure of 36 #'s was recommended.
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sidewall flexing causes the molecules to expand in tire,thereby increasing heat and pressure. check um before you move um that day.
(cold...not driven). want to break a coat hanger? see how fast you can bend it in one spot. don't get burned.
i bet the engineers knew that
(cold...not driven). want to break a coat hanger? see how fast you can bend it in one spot. don't get burned.
i bet the engineers knew that
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Correct me if I'm wrong but I would think Goodyear would probably be the one to work with GM in determining tire pressure. GM did not make the tires Goodyear did, or did I miss something?
30PSI cold is what the recommended pressure is on the stock tires on the C5, look on the tag on the door. If you are talking about aftermarket tires well then you need to check with the Manufacturer of that tire...or the tire shop where you got it to get the recommended running pressure. Most tires if you look on them will tell you what PSI not to exceed.
Running 35 PSI when it's hot out is about right. You will gain about 3-4 PSI going cold to hot. Stick with 30 PSI cold and you'll be fine..... unless you plan on running your car at Daytona at 200MPH for 500 miles.. then you might consider running Nitrogen rather than air
in all seriousness though if you really want to regulate the PSI and don't want to gain that much then like Mqn suggested get the tires inflated with Nitrogen.
30PSI cold is what the recommended pressure is on the stock tires on the C5, look on the tag on the door. If you are talking about aftermarket tires well then you need to check with the Manufacturer of that tire...or the tire shop where you got it to get the recommended running pressure. Most tires if you look on them will tell you what PSI not to exceed.
Running 35 PSI when it's hot out is about right. You will gain about 3-4 PSI going cold to hot. Stick with 30 PSI cold and you'll be fine..... unless you plan on running your car at Daytona at 200MPH for 500 miles.. then you might consider running Nitrogen rather than air
in all seriousness though if you really want to regulate the PSI and don't want to gain that much then like Mqn suggested get the tires inflated with Nitrogen.