Just dont get it - Tire pressure

I'm running e rated 245's (for now)not near as wide but only run about 30 in front and 25 in the rear empty if you drop the pressure they should ride and wear better

 

The alternative is to air down your tires further for a better contact patch. However, when you load up the truck you should bump up the pressures to what BFG recommends or what those inflation tables say. This is important for highway use but not really important for offroad.

 

I run 35 front and rear BFG KO2 E rated and all is good.
How’s your alignment?Are your wheels balanced correctly to the tires front/rear?

 

I got an alignment about two weeks ago. But I did have someone today stop me and say that my passenger front looked like it was toed in. But the chalk test doesnt show that and I can't feel any thing wrong. Yes, the tires are balanced pretty well I think. Sorta hard to tell because my old muds were so bouncy (they never were balanced well). It is a bit bumpy,but I think that is just the truck being a truck.

 

Hankooks Dynapro ATMs 265/75/16 set at 35psi. cold all the way around and wearing straight across. The key to getting the pressure right means that tire should be cold for at least 2 hours. I like to check pressure in the morning for that's when they will be coolest. keep doing chalk test when you find the sweet spot write it down and keep them there.
Good luck finding your sweet spot.

 

Yeah, I am going to do 35 front, 33 rear (cold) tomorrow and see what it is like

 

Firestone Lifetime Alignment. FTW

 

same I'm at 36

 

It isn’t down to holding the weight. The pressure they told him would support over 9000 lbs of GVW.

What they did was tell him the pressure that would get the new tires at the same same point on the load curve as the P stock tires at recommended inflation. That’s considered the best starting point to have the same ride quality and handling as stock when you switch tire sizes. But it is only a starting point really and for big changes in tire size or type you might adjust quite a bit from there.

Always wise to check the load curves for your final pressure of course.

Oh and thanks for the link, that is the most complete table I’ve seen so far, the others I have are missing a fair number of sizes.

 

How do you figure the 40-45 psi in a 285/75/16 Erated tire can hold 9k lbs? Not disagreeing with you, just don't see that psi anywhere for that weight. I didn't know if you had a formula or something to arrive at that figure

 

GVW is distributed over the four wheels, though of course not necessarily evenly between the front and rear axles. From the table that was linked a LT285/75R16 handles a load of 2340 at 40 PSI and 2540 at 45 PSI. So just using the lower PSI they gave you 4*2340=9320 lbs.

Similar story for stock TRD OR tires which at the door sticker inflation have a load of 2015 and 2115. Still well over the GVWR of 5500.

So it really isn’t about the tires potentially being too under inflated for the weight. All the various recommended pressures in this thread provide load handling way beyond the GVW. The vehicle manufacturer determines what point on the load curve the tires should be inflated to based on a number of factors beyond just GVW. When you change sizes the recommendation is to inflate the new tire to the pressure that gives it the same load handling as the original size tires at their recommended inflation.

It seems like BFG is telling you to inflate these well past the equivalent load point of the stock tire size. Seems like 35PSI at a load point of 2130 is the closest match to stock. So it seems like you finding them over inflated at 40/45 is to be expected. Likely 35 PSI is the correct starting point.

 

Oh hey - and I think I see why BFG screwed up. They didn’t account for the fact that the stock Tacoma tires are P on a light truck and thus the load curves are derated by 1.1. They used the standard P table and not the derated table when finding the stock load. If you make their same mistake you get 40/45 as they told you. If you do it correctly you get 35/35.

 

Damn, I wasn't thinking right. I was thinking that each tire was to hold the entire weight of the axle. Stupid me! That totally makes sense. Yeah, I am going to run them at 34front/32rear and see how they are.

 

Yeah, I don't think that they were accounting for the 1.1 either and I just learned about the 1.1 factor this week. Thanks again!

 

I’m at 35 all around on my st maxx e rated.... any less and it starts to hurt your mileage in my testing

 

u smart!

 

Where did you get this information? The larger the tire, the lower the pressure required to support a given weight. That is why a bicycle road tire is over 100psi, and a mountain bike tire might be 30. E rated tires do not require more pressure. E rated tires CAN hold more pressure, and therefore more weight. That is the only difference. What you are seeing is the proof.

Trust your chalk test. Do it after a reasonable drive to get the tires to a typical temperature. Once you get it right, check the pressure cold in the morning and use that as your reference. Add a few pounds for extended highway or loaded driving.

My truck weighs about 5,600 pounds and my 255/85-16 E tires are set at 32 front and 30 rear. One more thing. Tire gauges are all cheap. I've got three different dial type gauges that all read different numbers. The spread is 5 pounds!. I only use quality liquid filled industrial pressure gauges like Wika for my tires, and even they only claim 2% accuracy. Don't get hung up on a number. Get a good gauge, trust the chalk, and use the same gauge at the same temperature every time you check if possible.

 

E rated 265/65/17 KO2's for me. Running 32psi all around. If I did it again I'd probably go C-Rated, but at least E-rated tires should last a longggggg time on these trucks.

 

My tire guy put in 45 on my BFG's to properly set the bead. I'm running 35 in each now.
Did the chalk test and all is good. It's a good idea to drive in a mild serpentine pattern
when doing the chalk test..btw...not just straight.

 

I haven't noticed a huge difference in that. The rubber is still the same hardness.