Tire Manufacterer Or Auto Manufacturer

[kawtoy_77]

Tires will say right on them MAX infl. press, and obviously you don't wanna air it up to the maximum. The tires I just bought say MAX Press 44psi, and I put them at 40psi. A guy at work pointed out to me that tire pressure specs are on a sticker on the inside of the door. That sticker reads 35psi, but then my tire feels/looks squishy, not alot but a little. He says that what you SHOULD go by. I say what does GM know about tires that they didn't manufacture? Also, I upgraded from 245/70/17's to 265/70/17's so I can only imagine that there should be some difference anyhow. I am sticking with my between 35-44, and keeping them aired to 40psi

 

Anyone else with some different views?

[Matt_]

Tires will say right on them MAX infl. press, and obviously you don't wanna air it up to the maximum. The tires I just bought say MAX Press 44psi, and I put them at 40psi. A guy at work pointed out to me that tire pressure specs are on a sticker on the inside of the door. That sticker reads 35psi, but then my tire feels/looks squishy, not alot but a little. He says that what you SHOULD go by. I say what does GM know about tires that they didn't manufacture? Also, I upgraded from 245/70/17's to 265/70/17's so I can only imagine that there should be some difference anyhow. I am sticking with my between 35-44, and keeping them aired to 40psi

 

Anyone else with some different views?

 

The air pressure holds up your truck, not the tires. The tire manufacturers are only telling you what the max capacity of the tire is, which subsequently requires the MAX pressure (because the pressure holds the weight.. get it?). If you put an E-Rated 10 ply tire on your truck that had a max pressure of 80 PSI, would you run 80 PSI? no.... (well, you shouldnt)

 

So what does GM know about tire inflation? Well they know the weight of your vehicle, the weight its rated to carry, the dynamics of the suspension and the cornering/maneuverability of your vehicle.. ALL of which play a role in calculating the tire pressure.

 

Unfortunately, as you change tire sizes the "actual" required pressure does change as well and I don't believe there is a textbook method for determining your new tire pressure. Some people are obsessed with the "chalk test" or think you can just divide the vehicle weight by 4 and use interpolation to extract the PSI based on the max pressure vs. load on the tires... none of which take into account sidewall stiffness for handling.

 

With that said... for 1500 series trucks with tires sizes from stock till about 35x12.5, I don't think you could do any wrong keeping your tires in the 35-40 PSI range. (you can drop the rear tires down to about 30-35 IMO as well for when you're not towing/hauling). Anymore than 40 PSI and I think you're over inflating unnecessarily, and less than 30 PSI is under-inflated... all IMO of course.

[kawtoy_77]

I figure I am in "the range" anyhow. Not planning on going over 40psi, but may try 37-38 psi... I put a P-series tire that is rated 113T or Max Load 2535lbs @ 44psi Thanks for the info!

[rodram]

... usually, but not necessarily always a P-rated tire will give a max load spec at 35 psi

 

... if you are buying tires with a max load spec at 44 psi, this is likely NOT a "P" tire (check what the sidewall actually says), but sometimes called an SUV tire or an XL (extra load) tire ... these are not "LT" truck tires but a slightly tougher grade than "P" tires

 

... my rule is NEVER use tires rated for less than what is stated on the drivers door sticker, that is, never downgrade the tire size or load rating

 

... and then the max tire pressure for you will be somewhere between the stated max on the truck door and the stated max. on the tire sidewall.

 

... you are not going to find a spec that tells you minimum tire pressure ... but the discussion above that talks about minimum 30psi (and up to min of 40 psi if your tires are rated for that... depending on which load range of tire you have)...is a good guide

 

.. for daily driving I have 40-45 psi in my Load Range D tires (OE size and LT tire grade)

.. truck door sticker says 50 front and 60 back (this is for the maximum truck carrying capacity with those tires ... and I use those pressures when towing travel trailer)

.. tires say max 60 psi

[kawtoy_77]

Rod, lol... not an idiot here. It is a P-rated tire. Thats what it says on the sidewall and thats what I ordered. The LT series was much more expensive, and the P-series could handle quite a bit as I stated above, so thats what I went with. Thank you for your input.

[56kz2slow]

With commercial tires and RV tires, they often have a chart for the tire pressure for a given weight. The only way to properly use the chart is to have the vehicle weighed by axle, and divide by the number of tires on the axle.

 

Same size tire from different manufacturer can even require different pressure due to difference in the design or construction.

 

For even wear, the chalk test or driving through a puddle and checking the foot print is the closest you can get if no such chart is available.

 

The max pressure on the sidewall is only to be used if you put the maximum weight also listed on the sidewall.

 

Myself, I use trial and error and watch the tire for even wear, if it wears in the middle, it's over inflated, if it wears on both sides, then it's under inflated.

[y2kz71]

your fine at 40psi, that door sticker was for the tires that came on the truck

[kawtoy_77]

all good info guys, appreciate the feedback.

[wages999]

My truck says 35psi on the door also, but the tires wear funny at 35 psi. I run 40psi and the tires wear better.

 

My 2009 HHR says 32psi on the door frame. The tires look like they are squating really bad at 32psi. I bumped them up to 36psi to see if they looked better and I gained 1.5 mpg doing it. The tires have a max psi of 44, so I feel that 36 in them is fine.

[rodram]

My truck says 35psi on the door also, but the tires wear funny at 35 psi. I run 40psi and the tires wear better.

 

My 2009 HHR says 32psi on the door frame. The tires look like they are squating really bad at 32psi. I bumped them up to 36psi to see if they looked better and I gained 1.5 mpg doing it. The tires have a max psi of 44, so I feel that 36 in them is fine.

 

yes... these are two examples of where the tires on the vehicle may be different (an upgrade in load rating) from the OE tires that the door sticker refers to ...

[kawtoy_77]

I wouldn't wish the OEM tires (General Ameritrac's) on anyone.

[wages999]

My truck says 35psi on the door also, but the tires wear funny at 35 psi. I run 40psi and the tires wear better.

 

My 2009 HHR says 32psi on the door frame. The tires look like they are squating really bad at 32psi. I bumped them up to 36psi to see if they looked better and I gained 1.5 mpg doing it. The tires have a max psi of 44, so I feel that 36 in them is fine.

 

yes... these are two examples of where the tires on the vehicle may be different (an upgrade in load rating) from the OE tires that the door sticker refers to ...

 

 

These are all stock tires.

[elcamino]

What you are not taking in consideration is that as the tires heat up from driving, the air pressure increases. So if you are at 40psi, after 50 mile of driving at 60 mph you might be a 44psi and if the maximum safe operating pressure is 45 psi you are pushing the tire to the extreme limits of its design. Also, over inflated tires cause more heat to generate in the tire, the tire to have a different contact profile and for the center of the tread to wear prematurely. This can affect the safe operation of the vehicle.

[kawtoy_77]

So you are saying 60 psi is a no no?

[wurgs]

The pressures on the tire are when tire is cold. as pressure gets higher as you drive its not a problem.