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Discussion Starter #1
So what sort of pressures are everyone running on their V's? I know tire mfg will vary some on what their max pressures are but curious what everyone is running.
Mine have been low so I just upped the pressure to tire mfg max. Checked today for 1st time since I got the car and found they were all 31-32psi, thought the tpms would have triggered being that low..!

OHTSU FP8000 275/40ZR19 101W
Yokohama Avid Envigor 255/45R18 103W

Set all 4 corners to 50psi, max tire ratings are 51psi.
 

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'06 STS-V, '17 CTS-V
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Whoa, bro. The correct tire pressures for each vehicle are printed on a sticker in the driver side door jamb. The pressure on the tire is just that, the max pressure for the tire to achieve its highest load rating. Tire pressure is set by the car manufacturer labeling because the suspension is engineered to be in tune with it. You leave the pressure that high and your going to bald your centers FAST! The car isn't heavy enough to require max inflation like that, and it'll ride like SHIT.
 

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Discussion Starter #3
Thanks for the info, it is why I asked. I just filled them higher tonight, not even driven on them. I went higher pressure as I can feel them roll when I drop in to apex a long sweeper on my way to work. Felt like they were low so I checked sidewall..

Would the individual tire also not affect what the correct pressure is with regard to what the tire Mfg designed the tire to run at?
 

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Thanks for the info, it is why I asked. I just filled them higher tonight, not even driven on them. I went higher pressure as I can feel them roll when I drop in to apex a long sweeper on my way to work. Felt like they were low so I checked sidewall..

Would the individual tire also not affect what the correct pressure is with regard to what the tire Mfg designed the tire to run at?
No. The pressure rating printed on the car is the pressure rating regardless of tire choice. The car and it's suspension are set up for that pressure to handle properly. The tire obviously also needs to be able to handle the weight of the car, and that is the script, for example, "(103Y)" you see printed on the sidewall. The third safety factor is the speed rating of the tire, Z. You need a tire that can handle the both the weight and the potential RPM they will be subjected to. The manufacturer decided the correct pressure to run the tires based upon these two factors is in the low 30# vicinity, and designed the suspension to be compliant with that.
 

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So what sort of pressures are everyone running on their V's? I know tire mfg will vary some on what their max pressures are but curious what everyone is running.
Mine have been low so I just upped the pressure to tire mfg max. Checked today for 1st time since I got the car and found they were all 31-32psi, thought the tpms would have triggered being that low..!

OHTSU FP8000 275/40ZR19 101W
Yokohama Avid Envigor 255/45R18 103W

Set all 4 corners to 50psi, max tire ratings are 51psi.
The low pressure warning kicks on about 28psi...and I believe the high does at 40..
 

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Discussion Starter #7
No. The pressure rating printed on the car is the pressure rating regardless of tire choice. The car and it's suspension are set up for that pressure to handle properly. The tire obviously also needs to be able to handle the weight of the car, and that is the script, for example, "(103Y)" you see printed on the sidewall. The third safety factor is the speed rating of the tire, Z. You need a tire that can handle the both the weight and the potential RPM they will be subjected to. The manufacturer decided the correct pressure to run the tires based upon these two factors is in the low 30# vicinity, and designed the suspension to be compliant with that.
Ahh wasn't that part of the issue with the firestone, ford explorers rolling over though? Tire pressure ratings on tire vs vehicle decal??

Rode OK @ 45psi this am, but I will bring pressure back down.

My car had no high pressure warning with tires set 45psi and heat had them up to almost 50.
 

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'05 CTS-V
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No. The pressure rating printed on the car is the pressure rating regardless of tire choice. The car and it's suspension are set up for that pressure to handle properly. ... The manufacturer decided the correct pressure to run the tires based upon these two factors is in the low 30# vicinity, and designed the suspension to be compliant with that.
The manufacturer determined that tire pressure for the OEM tires. All tires are not identical. I would not run pressures lower than what GM specs (low tires pressures mean the tire flexes more and generates more heat, which can lead to tire failure), but there's absolutely nothing wrong with running a bit higher pressures. There will be some increased impact harshness, but you'll get better steering and transient response - it just livens up the handling and feel of the car a bit. I don't like the way any of my 3 cars feels if I put the tires at the OEM recommended pressures, so I run anywhere from 3-10# higher (depending on which car it is and which wheels/tires I have on it).

Ahh wasn't that part of the issue with the firestone, ford explorers rolling over though? Tire pressure ratings on tire vs vehicle decal??
Yes and no. Ford spec'd a tire pressure that was too low and almost certainly contributed to the problems, but that has absolutely nothing to do with the max pressure rating on the sidewall of the tire.

My car had no high pressure warning with tires set 45psi and heat had them up to almost 50.
That's definitely unusual. From what I've seen on a few vehicles, GM seems to use +/-10# for the high and low alarms.
 

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Discussion Starter #9
The manufacturer determined that tire pressure for the OEM tires. All tires are not identical. I would not run pressures lower than what GM specs (low tires pressures mean the tire flexes more and generates more heat, which can lead to tire failure), but there's absolutely nothing wrong with running a bit higher pressures. There will be some increased impact harshness, but you'll get better steering and transient response - it just livens up the handling and feel of the car a bit. I don't like the way any of my 3 cars feels if I put the tires at the OEM recommended pressures, so I run anywhere from 3-10# higher (depending on which car it is and which wheels/tires I have on it).
I know for a fact the tires on my car have a significant flex to the sidewall at factory 32# and I could feel them rolling on aggressive cornering. The sidewalls were also crushing to the point they looked like they might be low/flat so I checked it and saw 30# and immediately added air based on sidewall info then came here to ask. I ran it all day @ 45# and it felt great. maybe a TOUCH firmer, but also lighter feel to steering and better accel, less felt drag.. I will liekely drop down to 40# and leave it there for a few weeks and see how it goes.

Yes and no. Ford spec'd a tire pressure that was too low and almost certainly contributed to the problems, but that has absolutely nothing to do with the max pressure rating on the sidewall of the tire.
Yeah that is what I was referring to, the car MFG recommended to low a pressure vs what the tires actually needed.

That's definitely unusual. From what I've seen on a few vehicles, GM seems to use +/-10# for the high and low alarms.
Maybe GM knows that tire MFG rate tires of this size up to 50psi so thier +/-10 is set @ 40 so high alert is 50??
 

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My low warning is set to 25psi. I run mine at 28psi rear hot and 32psi front hot and have for 5 years. That also gives me the best wear on the tires.
 

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Thanks for the info, it is why I asked. I just filled them higher tonight, not even driven on them. I went higher pressure as I can feel them roll when I drop in to apex a long sweeper on my way to work. Felt like they were low so I checked sidewall..

Would the individual tire also not affect what the correct pressure is with regard to what the tire Mfg designed the tire to run at?
I believe Cadillac recommends 30 PSIG at all 4.... That's it.
You can run the pressure up to about 35 on track day to stiffen the sidewall f/ corners but I know on my CTS-V a warning would pop up when the tires got hot and pressure increased to 40 PSIG.
 

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I ran the stock run flats at spec pressure to 19k miles, and the rears wore WAY faster in the middle than at the shoulders. Just got a new set of rims/tires, and reduced pressure by 2lbs from the OEM door sticker recommendation on each corner (front 28 from 30, rear 30 from 32) to hopefully prevent it from occurring again.

Some pics of the new shoes slapped on for kicks. 10" wide rears wrapped in 285/40-19s, 9" wide fronts wrapped in 265/40-19s. The altered backspacing pushes the rubber right to the edge of the fenders for a wider and meaner stance. Love the look. And they'll look even meaner when I get back my calipers powdered the same color red, and the brakemotive drilled and slotted rotors installed on all four corners.













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I believe Cadillac recommends 30 PSIG at all 4.... That's it.
You can run the pressure up to about 35 on track day to stiffen the sidewall f/ corners but I know on my CTS-V a warning would pop up when the tires got hot and pressure increased to 40 PSIG.
Door sticker recommends 30 front, 32 rear. I dropped 2lbs from recommended in each corner due to the tire wear on the rears in the center of the tread. 32 lbs in the rear appears to bulge the center of the tire, resulting in uneven wear, as you can see in my pics selling the tires/wheels. Might run 30 all around though, as front tire wear was minimal.
 
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