I'm very surprised to see the door stickers on my 2010 Tahoe LTZ calling for 32 psi in stock tires. I generally run 38-39 psi in my SUV tires, am doing that now. Seems like most SUV's will be spec'ed at 35 psi on the door, really surprised to see the 32. Anyone know why? I can't imagine many people run pressure that low.

 

Dave,

Smart idea questioning that !

Though it's hard to second guess GM, I'd say they're trying to soften your ride up for you. And, that's even hard to believe, given the downside to lower pressure.

The 38-39 psi you've been running, is a lot better than the pressure listed on the Drivers Door, though in reality, that still isn't enough for the usual LT type tire run on our Burbs and Hoes. For some, it's real easy to forget, that even with a moderate load, our vehicles can easily weigh 6000 lbs or more.

There's a Maximum Cold Inflation Pressure (MCIP) which is stamped on the sidewall of each tire.
I recommend that you air your Tires up to within 10% of that listed pressure.

And here's why...
1) Well/higher Inflated tires get better gas mileage.
2) Handling/control (cornering) is greatly improved.
3) When having to do Hard Breaking, the Tire resists compression, and has better traction and ability to stop your vehicle.
4) When encountering a Road Hazard (curb/chughole) higher pressure resist compression of the Sidewall, limiting the injury to the Tire.
5) When Sidewalls don't flex as much as with lower pressures, Tires run cooler and have a vastly lower failure rate.
6) At High Speed, higher pressure enhances the overall rotational stability/roundness of the Tire, which improves its balance, creating more consistent contact with the Road Surface.
7) Tread Depth Patterns are set up, where over the life of the Tire, that they wear more evenly and provide longer life, when the Tire is inflated in its higher range of pressure.
8) When Towing, or carrying heavier loads (multiple passengers or cargo) the Load Rating of the Tire cannot be assured, unless the Tire is aired up at or near its Maximum Cold Inflation Pressure*.
9) Increased pressure maintains the footprint of the Tire, stabilizing the separation of the spacing of the Tread Grooves, allowing it to discharge Water better, on wet surfaces.

The above advantages, are well worth the minor tradeoff of having a slightly firmer ride.

Note*:
The Maximum Cold Inflation Pressure is the Manufacturers guarantee that the Tire can be safely and reliably operated at the pressure listed thereon, for its life.

 

Thanks for that info. The max cold inflation on these tires is 44 psi so your "within 10%" would put it at about 40 psi. I've run a lot of tires at 40, but usually on 16" or 17" wheels with 70 or 75 series tires with the much taller sidewall. With these 20" wheels and 55 series tires I figure a bit lower might make sense, no need to have the rock hard ride.

I guess I just can't imagine why GM would put 32 as the recommended pressure, just doesn't make any sense given the capability of the vehicles and type of tires on them, just as you said.

 

My Mercedes e320 4Matic calls for lower pressure in the front - I notice the best ride when they are set up the way the panel indicates.

It could be to the increased front end weight that they call for this...or the suspension set up. Dunno.

I do know that when I inflate to near sidewall suggested PSI on the front...the car hops all over the place..that can't be good.

My tire guy set up the fronts on the Suburban (2001 with regular 10 ply)...with 60psi in the front. It seems to ride ok...but I'll be adding some more to change things up an see how it rides!

 

Those 10 ply E rated should have max cold inflation of 80 psi. I ran them on my '97 Suburban 2500 diesel and normally ran 60 psi front, 55 psi rear, when loaded up or towing would go up to 65 psi all around. Running E rated tires at 80 psi is like driving on rocks!

 

I agree that 32psi is too low, and I like the idea of running at 10% of MCIP.
I had to tow my brothers boat a couple of weeks ago and looked up the MAX rating on my tires (Goodyear Wrangler HP). I found 3 tires had a rating of 51psi and the 4th was rated 44psi. All tires came with the vehicle (used 2011 Tahoe LT). They were manufactured a week apart in 2010 (DOT codes). The only difference I've found is the number of tread plies 5 plies vs. 4 plies.
Should I keep all tries at the same pressure when towing and what pressure would you recommend? I run 35psi for around town driving. Are there any other issues I may encounter with this setup?
Thanks
Bruce

 

Dave,
Running the higher pressures with a Low Profile Tire (50R/40R/etc) is very important ! Consider how little room you have with them, between the Rim and the Road. Cheaply made Low Profiles, are Crosscuts looking for a place to happen !

Bruce,
How strange ! Do not exceed the Maximum Cold Inflation Pressure on any tire. There is absolutely no way you can compensate/equalize a situation like that. Is it possible that it may be "P" rated ? I'm surprised that you haven't noticed issues with handling. I would suggest that you seek out a replacement Tire for the 4 ply.

If you choose not to do that...
When Towing, I would definitely run the 4ply on one of the Fronts, at about 42-43psi. The others at 46-48psi. I suspect there's quite a bit of difference in the Load Ratings between those two as well !

grateful1,
I really can't speak to the "hopping" problem on your Mercedes. We're talking a different type Suspension Assembly, Shocks and type construction of the Tires (they're not LT's).

-----------------------
We need to keep in mind that our Burbs and Hoes are Trucks !
The only "forgiveness" toward a good ride is their weight.
Also, the vast differences in what each of us, considers an acceptable ride,
and how much of that we're willing to trade for enhanced performance.

 

LOL - yup!

Next time I get a lesser rated tire - I don't tow that much!


-----------------------

All I was saying with the Merc. reference was...test things out....you'll know what feels right!

 

That may be ok
Here's a way to determine what Load Rating you need.

The situation is that...
Under extreme circumstances of Corning and Breaking, that as much as 90% of the total (loaded) weight of your vehicle, can be placed on any two of the Tires.

Now to calculate that, I'll use my vehicle as a reference, and you can put your numbers in for yours.

The dry weight of my vehicle (title weight) is..
5700 Lbs.
My load capacity at 1/2 ton is...
1000 Lbs.
That makes my total permitted Gross Weight at...
6700 Lbs.
Distributing that between two Tires, requires a Load Rating between...
3015 Lbs, and 3350 Lbs per Tire. (for me)

Many LT type Tires of the same size, are made in several Load Ranges.

A Load Rating is like an Insurance Policy.
Your choice is, how much coverage do you want ?

 

Thanks SW,
The 4 ply IS on the front.
The tires have the same load rating 2535 lbs. Have not noticed any handling issues.
What is the "P" rating?
Both tires have "Standard Load" on them.
I ran 40psi all around (a compromise) when I was hauling the boat, and it handled fine. It was just a 2.5 hour trip. Next time I haul the boat, I'll up the pressure.
I need to check the spare tire to see what it it's rated.