Luke27617

iTrader: (2)

Here it is an interesting reading I have found on Tundra forum.

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Proper Tire Air Pressure (Author unknown, but makes good sense.)

I worked for Michelin Tire Corporation for 7 years and Yokohama Tire Corporation for 11 years. I have given numerous seminars on tire maintenance and especially how to determine the correct tire pressures. So here goes.

The pressure on the sidewall of the tire is the maximum pressure at the published load at approximately 55 mph. (The speed can vary somewhat, but it is not important for this discussion.)

The air pressure is required to support the load that the tire must carry in such a manner that the tire flexes at the designed place on the sidewall of the tire.

If the load on the tire changes, then the air pressure should change accordingly to keep the tire flexing at the proper place. The reason for correct air pressure is to prevent the tire from overheating. It was put together with heat, and it will come apart the same way. An under-inflated tire will eventually self-destruct due to excessive heat build-up. An over-inflated tire will ride harshly and be more likely to burst upon impact.

To determine the correct air pressure, check the pressure when the tire is cold. Run the tire for several miles at highway speed. Stop and immediately check the air pressure in the tire. It should be higher than when cold, but no more than 10% higher.

Now here is the hard-to-believe part. If the pressure is more than 10% higher, you must ADD AIR and test again. For example, you start with 50 psi cold. If the pressure is 60 psi when hot, you have exceeded the (10% in this case,) 55 psi maximum safe heat build-up pressure. You must ADD AIR. In this case I would add 5 psi, which would take the tire to 65 psi when hot. After you run the tire again you will find the pressure actually drops because the tire will run cooler. The heat build-up causes the tire pressure to increase when under-inflated.

On the other hand, if the 50 psi cold pressure does not change when hot, you have more air than needed. You can remove 5 psi or so again when they return to cold. Like the next trip you take.

So, a fully loaded rig will require more air in the tires than one with empty tanks and a light load on board. Always err on the side of over-inflation. Thus, the maximum sidewall pressure indicated on the tire is usually used. It usually is more than needed. Each axle has its own requirement based upon the load on that axle.

Craig B

Wow, I drive my GX in the snow, that's what I purchased it for. My LS 460 sits in the garage all winter... What do you drive in the snow?

Booyah

I keep mine at 35PSI and My GX lives for the snow, and we do get alot.....lol

Koz

What is also important is compensating for ambient temp, altitude and normal pressure loss from time. For every 10 degrees drop in temp you will lose 1 psi. For every 1000ft loss in altitude the pressure decreases a half pound. For every month you will lose 1 lb of pressure.

Tire life decreases 10 percent for every 10 percent it is under-inflated.

Koz

Craig B

Same here 35 PSI in all four tires...

MickeyS

I keep my tires at 36psi and so far it's been a comfortable ride. I use my GX for everything including the trips to the mall, which I hate, because I can't easily find a corner spot away from all the other who like to ding car doors

Luke27617

iTrader: (2)

No dings for me. Every mall in Raleigh area offers a free valet parking for Lexus customers. I think it is a great advertising by the Local Lexus stealer.

I am still playing with PSI. I am trying to figure out what is the best pressure to minimize vibs in steering wheel I have at random intervals. The only unfortuneate problem with GX. I gave up fighting stealer to repair it and leanring to live with it.

SaniDel

LOL ... we don't drive when we don't have to. We are retired, live in a maintained community and have no "must go" commitments like we used to have ... and most people still have. Yes, we are very fortunate and someday you will be in a similar situation, but don't quit your day job quite yet. ;-)

So, why do we own a GX 460? Would you accept that it is the best vehicle we have ever driven? My wife and I have owned only one vehicle at a time, we have owned many vehicles of many types, but only a luxury SUV meets the most ... if not all of our needs and wants. If it would fit in our townhouse garage we would own an LX 570 ... we owned six LX 450 and 470s, but the 570 got too big!
Regards,

SaniDel

Craig B

I'm in a similar situation, I don't have to be anywhere either, but I don't like being stuck at home. I like to go to the gym and other places. This is my 6th Lexus. I keep my LS 460 in the garage all winter.

Regards,

Oldmanb777

Wife's GX has about 2000 miles on it now. Got it in Feb. We have not had it long enough to do much. But before heading out for a few days, I usually do a walk around. Check tire pressures, fluids etc. So I looked at the sticker on the door. It says 32 psi cold. Ok so load range "B". All 4 tires are @ 41 psi. The tire side wall says 51 psi cold max. I think thats load range "C". similar to what I run on the Jeep. My truck uses load range "E". Back to the question. The vehicle is seldom loaded to max capacity, or max tire pressure would be warranted. But 32 psi seems very low for everyday driving. Car seems to handle fine at 41 psi. I have never adjusted it since it came from the dealer, so that's what the dealer adjusted it to when we bought it. Just from looks at what you can see of the contact patch, it looks ok, but that's not much to go on. So what's your experience? You run 32 psi? or 50 psi? I seldom run the sticker pressures on my other vehicles. I adjust them to what I'm doing with the vehicle at the time. Just no experience with this vehicle yet.

bbqsoup

I agree that 32psi is pretty low. You will definitely experience the Lexus comfort feel
I have mine set at 34-35 now but will pump it up around 36-37 for the incoming roadtrip.

Craig B

I have all four set at 35 PSI, I did the same thing with my 2010 GX 460 as well.

Acrad

I've run mine at around 38 then for testing last month did lower to around 32-33. It did seem to make for a smoother ride and no noticeable change in MPG but I'm sure there is some effect.

mattau

I run 33 psi. I usually follow recommended psi plus 1 to 1.5 psi in all of my cars. It's usually better to be over-inflated than under right?

Oldmanb777

Ok thanks. i'm going to try different pressures as soon as I get a chance. I usually run a bit higher than the placard, but depends a lot on the tire I'm running at the time, and what i'm doing at the time. The Load range C on the Cherokee, I run 35 most of the time, down to about 18 off road. The truck I run close to 50 in front and 48 in the rear when no load in it, Up to 80 when heavily loaded.