What psi should i run?

Stock tire is a 265/70/16/112; @ 30 psi it has a load capacity of 2,149 lbs.
Euro metric and P metric tires are de-rated for use on trucks and SUVs. When you switch to an LT, you need a psi that attains a 1,954 lb load capacity...2,149÷1.1=1,954
A LT265/75/16 has a load capacity of 1,986 lbs @ 37 psi.

Air down pressure depends on terrain and speed. Generally, you don't start getting the benefits of airing down until 20 psi or below. Experiment...

 

Thank you!

 

Can I play this long running game?

Got new LT265/75/R16 Wildpeak AT3W on. Sneaky lil shop boys had them aired up to 42psi front and 44psi rear.

I just chalk tested warm (1pm, but not driven)

I am now at 34psi front and 30psi rear

I am stock no extra weight

 

I will chip in too.... Currently running 295/75/16 BFG KO2... Running 30 psi all around for ride comfort.
FYI. Every truck set up is different. Example, front bumper, winch, skid, slider, camper shell, constant weight on bed and etc... will determine what psi you are running. So there is no set psi, one will have to determine that them self. What work for you, might not for other...

 

With an LT295/75/16 @ 30 PSI, you are at 2,020 lbs load capacity...the formula method requires 1,954 lbs load capacity. So, you're real close...
With LTs, generally, the larger the tire volume the less psi is required for the same load capacity.

I dislike the chalk method...
-it's a holdover from the days of bias plies; modern radials do not react the same
-doesn't account for dynamic loading of the tire
-doesn't account for mounting on a non-nominal rim width, which changes tire section width; chalk footprint expectations do not change
-conditions to do a proper chalk method are difficult, if not impossible to replicate
-according to purveyors of the chalk method...loading 3 adults or any significant load requires re-chalking

 

You are right....

 

I am going to bring up a fact that most people dont consider. Toyota doesnt set the door placard psi only for load rating. They do it for ride comfort and fuel economy since the tires are always larger than they need to be for load carrying capacity of the vehicle. So while it is safe to use this to calculate to different size tires you will always end up wth too high of a psi when converting from SUV (p-metric) to LT tires. So you need to look at the Gross Vehicle Weight Rating (GVWR) which if you are looking at a 3rd gen is 5600lb then you divided by 4 to get 1400lb per tire minimun. From there you can figure out your minimun pressure based on your new tires size. But this minimum psi is not going to end up with the best ride charactersitics and you will need to adjust to get the proper contact patch. With all of this in mind I think the chalk test is a great starting point.

 

Inflating for mpg and ride comfort seem contradictory, no?

It's GVWR x dynamic load & safety factor = inflated load capacity

The placard has a 2,149 lb load inflation for P and Euro metric tires. This translates to 1,954 lbs load inflation when an LT is used.

Dynamic & safety load factors:
1,400 x 1.54 = 2,156...P and Euro metric
1,400 x 1.40 = 1,960...LT

This is the load chart for a euro metric 112 SL; what comes on the Offroad and Pros.
According to you, inflation psi would be below 22 psi. Notice the load capacity at the recommended 30 psi; 2,149 lbs.

 

It only seem contradictory if you consider that low tire pressure would not be comfortable driving then MPG/comfort work together.
I think I missed where the 1.54 and 1.40 saftey factors came from? You may have said it before in the thread but I am sorry I missed it.

I am not trying to say that your extra saftey factors are wrong I am just saying that if you have an LT tire I think that you will be over inflating it and it will be a harsher ride than you will need for Load.

 

Check my edit...

 

Sorry I understand how the chart works it is taken from the "ETRTO manual" which is for european tires. I am just trying to understand where the Dynamic & safety load factors (1.54 and 1.4) came from? I am pretty possitive that those load values are dynamic load conditions.

I am not suggesting that you run your OE tires at 22psi but you could run the tires on your vehicle at 22 psi with the tire having issues. Although You wouldnt want to do this for the lifetime of the tire.
I am not stating to run at minimum pressure what I am stating is that when you convert SUV to LT tires they are not created equal thats why I am trying to understand where your saftey factors came from.

I think the confusion is coming from that fact that you are trying to use the placard psi to determin the load that the tires need to be and I am trying to say they dont need to handle that much load. They are putting the tire pressure that high for handling, mpg, and comfort.

Take a look at the sticker to the right of the placard it says Front Gross Axle weight is 2,755 lb or 1,377.5 lbs per tire. Rear gross axle is 3,110 lb or 1,555 lb per tire. This is the most weight you should put on the front and rear axle.

 

You're saying inflate to GVWR...or 1,400 lbs at each tire.

The stock tire(a euro metric 265/70/16/112) at it's recommended 30 psi is 2,149 lbs of load capacity...
2,149÷1,400=1.54

An LT only requires 1,954 lbs load inflation because euro and P metric tires are de-rated for use on suv/trucks.
2,149÷1.1=1,954
1,954÷1,400=1.40

If you want to disregard it for the reasons you mention...I'm not going to try to convince you otherwise. But, there it is.

 

I am not say to inflate to GVWR or GAWR because this would not be a very good footprint or ride. I am saying that it is safe and you dont need the 2,149lb that comes with the vehicle.
Toyota isnt trying to get 2,149lb of load capacity. That value is just what came out once Toyota got the right footprint and response of the tire. Also you shouldnt load the front axle past 2755 lb and the rear axle past 3110 lbs. I am just trying to work through the facts so that people arent overloading their LT size tires and then saying that they are super stiff and uncomfortable because they are trying to meet a load that they dont need.

You can continue to do it the way you have been and be safe.

 

I drove the truck around. It rode better, was more comfortable, quieter, and people were rubber necking because I looked so cool with my tires at 34/30.
Also I didn't make my chalk test perfect, because it was mid day and the tires will cool off, also once they get heated up I figure they will gains some PSI and that can counteract any additional common loads (aka SWMBO).

If it is winter or hauling I will add some PSI, if I am off roading then I will decrease it.

In the meantime I rotate every 5k and won't worry too much

 

Wow, this tutorial/sticky is creeping up on 11 years old. After a thorough skimming of stuff from Chris and his chalk, plus the more recent analysis from Pete & Split I have decided 32psi all round, or 34 in front and 32 in rear is what my ideal pressures will be. That of course depends on the lazy factor and how I have about a dozen other things to do before fixing my air pressure. Anyway, really neat info here. Thanks for all the input from everyone!

 

This is going to be my monitor, LoL

 

Status update: Made a point to check my pressure this afternoon and (w/ the Alabama heat) I'm 35 front/ 34 rear. No way to easily fix my TPMS light until I go back to stock rims & etc. but am glad my tires are good now. This was my first check since buying the truck a week ago. Maybe the service tech is a TW lurker.

 

I don’t know about anyone else but if I run rear tires over 35 psi my backend spins when taking turns from a stop. I’m running 18’s on my 4x4 Limited DCLB. Pretty much 32 all around but I don’t carry much ..

 

35

 

Sticking to 32. Increase it depending on road conditions.