What PSI are you running in your Tahoe tires?

KMeloney · September 9, 2003

Hey all,

Currently (and the rear sidewalls are bulging) I've got all four tires of my '02 Tahoe Z71 (17" wheels) @ 30 lbs PSI -- but I just found the paperwork where my alignment guy recommended 40 lbs in the rear tires and 38 lbs in the fronts.

Before putting more air in, I thought I'd ask you all what you're running in your tires (or what you think I ought to be running).

Thanks, folks!

-Kirk

Bish · September 9, 2003

Depends on what tires you have and what conditions you drive.

For me, I have Michelin LTX M/S LT265/75R16 Load Rating C. I run mine at 40psi unless I am towing. If towing, I bump them up to 48psi in back and 45 in front. If I'm offroading in the sand, I air down around 15-20psi

My oem tires were P265/70R16 (P-rated). Their max pressure was 36psi. Don't go over the max on the sidewall as that is the max that particular tire is rated for. Go over and you risk a blow out. When I towed, I would routinely exceed the load rating of the oem tires.

Be carefull over-ionflating P-rated tires!!!

Tree_Hugger · September 9, 2003

What does your sticker say your tire pressures should be?

SilveradoWV · September 10, 2003

I have 265/75/16s load range D and I run anywhere from 50-55 psi. Load range C I would run 45-50 prolly!

KMeloney · September 10, 2003

What does your sticker say your tire pressures should be?

Well, it says 30 lbs "cold inflation" (or something to that effect). Now, what's THAT mean? And since it's in the 80's here in Philly, should I be adding more air at the moment?

Thanks!

-Kirk

katz · September 10, 2003

FWIW, I'm running 35psi all the way around on my '96 Tahoe.

Tree_Hugger · September 11, 2003

What does your sticker say your tire pressures should be?

Well, it says 30 lbs "cold inflation" (or something to that effect). Now, what's THAT mean? And since it's in the 80's here in Philly, should I be adding more air at the moment?

Thanks!

-Kirk

Cold inflation means after you haven't driven for at least 8 hours, or have driven less than a mile from full cold. Normal running raises the temp and therefore the pressure by about 4 psi.

No, the ambient temperature makes no difference to the pressure you should use. But if it changes a lot, you should re-check your tire pressures...

If these are the original spec tires, you should run them at the recommended 30PSI. Higher pressures will give you a rougher ride, your tires will wear out in the middle of the tread, you will get less traction, and possibly better gas mileage.

HTH.

ClipperSkipper · September 11, 2003

We run close to max rating on work trucks, you need to read

the max inflation on the tire itself, and see what works. If we new the

rating it would be easier. 40 psi2 should keep you from riding on the edge

of the tire.

Have a great one!

KMeloney · September 11, 2003

If we new the
rating it would be easier. 40 psi2 should keep you from riding on the edge

of the tire.

Thanks for the replies, folks!

The max rating on the tire is 44 lbs. The sticker in the door calls for 30 lbs. The alignment guy recommended 38-40.

Based on all of this info together, is there a consensus as to what to run?

I've already installed Ford keys and raised the front of the Tahoe a couple inches, so my ride is "tighter". As such, I'm not too concerned about the ride being firmer with more PSI in the tires...

...I just don't want 1) to be in danger of tire problems, and/or 2) to have the sidewalls bulging from under-inflation.

Thanks!

-Kirk

Tree_Hugger · September 11, 2003

I suspect you're not going to get a concensus on this. Some of the advice you're getting is from guys who may be running different tires on 'work trucks' and thus operating under different constraints.

There are basically 3 critical objectives.

1) Safe load handling

2) No undue tire wear

3) No overheating.

Understand first that GM in consultation with the OEM tire manufacturer has done extensive calculations and testing and the recommendations on your sticker represent their best judgement.

If you have changed the original tires to a different tire, and particularly to a different size of tire, they no longer apply...

On the tire wall are two pieces of information you need Max Inflation Pressure, and Max Load.

These are federally mandated requirements. The Max Load is at that Max Inflation Pressure.

You also need to know the GVWR (maximum gross weight) of your truck.

Then do the calculation:-

Your calculated required pressure = (Max Inflation Pressure (=44) x GVWR) / (Max Load x 4)

You'll probably find this comes to about 30, if you have your original tires.

If not, then set the pressure to the calculated value.

Now to test...

Make a chalk mark all the way across the tread. Drive a few tire revolutions.

Look at where the chalk is worn off the tread.

If the outside is worn more, you are under inflated. Add 4 psi and try again.

If the center is worn more you are over-inflated (your truck weighs substantially less than it's maximum rating). lower pressure by 4 psi and try again.

If either edge is worn more than the other edge, you need an alignment. Get it done and start again.

Now you've got the tread flat on the road, like it should be. Drive about 10 miles at at freeway speed. stop and put your hand on the sidewall of each tire. The tire should feel no more than 'hand-hot'. You should feel no discomfort keeping you hand on the tire for as long as you want.

If the tire is hotter than this, add 4 psi and try again.

The reason for doing the tests in this order is that differently branded and sized tires may not be able to achieve correct wear patterns on your truck (usually this is when someone has enormously up-sized their tires), and this routine at least achieves safety at the possible expense of tire wear.

You may find that the optimum tire pressure leaves the handling a little 'squirrely' (again usually this is when tire size is greatly upsized). If so, then increase the tire pressure by 4psi, or until your handling feels good to you. (my Jeep is like this, every test says 22psi on the tires I'm using, but I run at 26 - 28 because the handling feels sloppy at the correct pressure.) This will result in increased tire wear (decreased tire life), but I already get high mileage from the tires because they are lightly loaded.... So I prefer to stay and feel safe.

HTH.

Bish · September 11, 2003

I suspect you're not going to get a concensus on this. Some of the advice you're getting is from guys who may be running different tires on 'work trucks' and thus operating under different constraints.
There are basically 3 critical objectives.

1) Safe load handling

2) No undue tire wear

3) No overheating.

Understand first that GM in consultation with the OEM tire manufacturer has done extensive calculations and testing and the recommendations on your sticker represent their best judgement.

If you have changed the original tires to a different tire, and particularly to a different size of tire, they no longer apply...

On the tire wall are two pieces of information you need Max Inflation Pressure, and Max Load.

These are federally mandated requirements. The Max Load is at that Max Inflation Pressure.

You also need to know the GVWR (maximum gross weight) of your truck.

Then do the calculation:-

Your calculated required pressure = (Max Inflation Pressure (=44) x GVWR) / (Max Load x 4)

You'll probably find this comes to about 30, if you have your original tires.

If not, then set the pressure to the calculated value.

Now to test...

Make a chalk mark all the way across the tread. Drive a few tire revolutions.

Look at where the chalk is worn off the tread.

If the outside is worn more, you are under inflated. Add 4 psi and try again.

If the center is worn more you are over-inflated (your truck weighs substantially less than it's maximum rating). lower pressure by 4 psi and try again.

If either edge is worn more than the other edge, you need an alignment. Get it done and start again.

Now you've got the tread flat on the road, like it should be. Drive about 10 miles at at freeway speed. stop and put your hand on the sidewall of each tire. The tire should feel no more than 'hand-hot'. You should feel no discomfort keeping you hand on the tire for as long as you want.

If the tire is hotter than this, add 4 psi and try again.

The reason for doing the tests in this order is that differently branded and sized tires may not be able to achieve correct wear patterns on your truck (usually this is when someone has enormously up-sized their tires), and this routine at least achieves safety at the possible expense of tire wear.

You may find that the optimum tire pressure leaves the handling a little 'squirrely' (again usually this is when tire size is greatly upsized). If so, then increase the tire pressure by 4psi, or until your handling feels good to you. (my Jeep is like this, every test says 22psi on the tires I'm using, but I run at 26 - 28 because the handling feels sloppy at the correct pressure.) This will result in increased tire wear (decreased tire life), but I already get high mileage from the tires because they are lightly loaded.... So I prefer to stay and feel safe.

HTH.

Well said!!!!

KMeloney · September 11, 2003

Wow! Thanks much!

-Kirk

PS -- Am I the only one here with a stock-tired/wheeled '02 Z71?! Didn't get much feedback from anyone else with a Z71 Tahoe... But thanks to those who did chime in!

Markeaux · September 12, 2003

I'd keep them at 30. I don't have 17's but my 16's are not much different. I had fair performance with the stock 265/70-16 Firestone Wilderness LE's, then much, much better performance with Pirelli Scorpion Zero 285/65-16H but they rode a bit on the firm side, so I recently switched to Yokohama AVS S/T 285/70-16H which are superb although I miss the wide look of the Scorps ... I ran all of the previous at 30 all around, the Scorps were pretty wide for the stock wheel but wore perfectly.