Any experience with Big O Big Foot A/T?

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The relationship is not linear. I posted a big long technical threat on this a while back, including links from major tire manufactures discussing the issue.

https://forum.ih8mud.com/showthread.php?t=111671

See also the tire faq we wrote.

The proper way to determine the proper inflation pressure is to take the load capacity of the oem tire at the pressure recommended by Toyota, adjust it down by 9% (I believe that is the adjustement factor required for safety by Dot), then cross reference that load (which is about 2400 pounds if I remember correctly) to the load chart for the tire you are running. These charts are actually done by Tire size and rating (LT or P metric). For a LT 285/75/16 that comes out to about 42 psi.

FYI, at any pressure a LT285/75/16 Load Range C, D, and E will all have the same load carrying capacity. The difference is that a C rated tire caps out at 50 psi, a D at 65 psi, and an E at 80psi, which allows for higher capacity (due to stronger sidewalls to handle the extra pressure).
 
Jule said:
Cary, where did you hear rule about what pressure to run LT tires at vs. P tires? Is the pressure vs. load capacity a linear relationship?

The tire shop recommended 35 psi to me. (They may say that to everyone though.)

I figured that made sense because the D range LT265/75s are rated for 3000 lbs each at 65 psi, and my TLC weighs about 6000 lbs with the family in it. That is 1500 lbs a tire, half of the rated capacity, and 35 psi is just over half of the rated cold pressure.

If I had the TLC completely loaded down I would run it at higher pressure.

My D range tires are rated for 3000lbs @ 65 psi (46lbs/psi), my E range tire is rated for 3450lbs @ 80 psi (43lbs/psi). It seems like it is approximately a linear relationship.

:confused:
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I trust the guy at my Big-O shop and he recommends 36psi. I've run 45 psi and didn't like the ride at all. Drove like a tank. . .not just jarring, but darty too.

Perhaps the ride would be different if my rig was armored.
 
Cary, thanks for the article on tire pressure. Sigh, if I understand the general gist, the most important thing is to identify the load capacity of the stock tires at the recommend pressure (2300 lbs) and carry that over to LT tires. In the absence of a load vs. pressure curve, using 46lbs/psi that would be 50 psi for a2300 lbs. That feels overinflated to me, but maybe that is appropriate pressure.

New2mud, the 265/75R16s are the same diameter as the factory tires (speedometer is dead on) and the Big O ATs come in three load ranges: P metric with 114 like the factory tires, and the D and E ranges. They only come in load range D for 285/75R16s.
 
Jule said:
New2mud, the 265/75R16s are the same diameter as the factory tires (speedometer is dead on) and the Big O ATs come in three load ranges: P metric with 114 like the factory tires, and the D and E ranges. They only come in load range D for 285/75R16s.
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If you are running the P metric tires, use the factory recommended 32 psi. If you are running the D or E range LT tires, use 42 psi. Yes it will feel firmer, that is because they are LT tires and they don't ride as nicely. That is one reason that many SUV's come with P metric tires now.
 
KANE said:
I trust the guy at my Big-O shop and he recommends 36psi. I've run 45 psi and didn't like the ride at all. Drove like a tank. . .not just jarring, but darty too.

Perhaps the ride would be different if my rig was armored.
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Don't bother letting facts get you way, after all that highly trained professional with an 8th grade education at Big O knows far know than the tire manufactures, Tire Rack and the DOT. Why don't you ask that professional how he came up with 36 psi, I would love to hear his rational. I know that I can explain mine.
 
cary said:
The tire you want is called a Bridgestone Revo A/T.
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Cary, I do appreciate the outright recommendation--really do. Only thing is, I have a personal and emotional reason to not by Firestone/Bridgestone products. Ever. I know I may be foregoing a great tire, but need a recommendation beyond Firestone/Bridgestone.
 
new2mud said:
Cary, I do appreciate the outright recommendation--really do. Only thing is, I have a personal and emotional reason to not by Firestone/Bridgestone products. Ever. I know I may be foregoing a great tire, but need a recommendation beyond Firestone/Bridgestone.
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You are going to have to slide along the scale then. As you get better off road performance, you are going to give up some on road performance. My recommendations for a slightly more agressive tire would be:

1) BFG All Terrain (BFG is owned by Michelin)
2) Yokohama AT/S

If you are want to keep the best highway handling matters you can get the LTX M&S in a 265/75/16 and 285/75/16 both in LT fitments but you will give up some off road traction and durability.
 
I've also seen some good reviews of the Nitto Terra Grapler--thoughts on how these compare to the Revo's?

Again, looking primarily for on-road performance, but need a definite step up from the stock LTXs for off-road.
 
The Terra Grapler is supposed to be a good tire, but I have no experience with it. It is supposed to be identical to the Toyo A/T tire.

Given you are not concerned about snow performance, my first choice would probably be the Yokohama.
 
cary said:
If you are running the P metric tires, use the factory recommended 32 psi. If you are running the D or E range LT tires, use 42 psi. Yes it will feel firmer, that is because they are LT tires and they don't ride as nicely. That is one reason that many SUV's come with P metric tires now.
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So are there any drawbacks to running 36 vs 42?

BTW, don't doubt my tire guy. He has a 10th grade education.
 
KANE said:
So are there any drawbacks to running 36 vs 42?

BTW, don't doubt my tire guy. He has a 10th grade education.
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Yep.

1) Accelerated tire wear.

2) Lower Gas Mileage.

3) Potential for blowouts due to overheating the tire because of overloading due to running underinflated.

4) Worse Handling, especially in an emergency.



Your tire guy has a 10th grade education. That is like a graduate degree for most tire guys.


P.S. I know they ride like crap at 42psi vs. lower pressures, but that is part of the tradeoff of LT tires. They are more durable but ride quality is not priority one. One way to help this, run them at 50psi for a week and then drop them to 42psi, it will make a difference.
 
I'll try 42 for a while. Maybe that is the reason for my mileage drop.

I was joking. I have no idea what his level of education is. My tire guy has got to be the smartest dumb guy I know. He owns the place.
 
When I first got my Nitto's (295 A/T) I ran 40 psi, they wore in the center, crowned and the side tread blocks were barely touching the ground. Did the chalk test and it showed the best pressure to be 32 psi for even contact. I run 30 psi around town and 35 psi on trips.

The ideal pressure depends on vehicle weight, rim width, average speed, temperature, tire type and construction, etc. Slightly under inflated tires wear the outside of the tread, provide more traction, increase roll/sway, increase ride comfort and take more fuel/power to turn. Over inflated tires wear the center of the tread, provide less traction, decrease roll/sway, ride like $&!* and take less fuel/power to turn.
 
I can vouch for their warranty. I had Big-OT AT on my 96 80. I moved to Scotland from Colorado and had issues with 3 of the tires over time (nails I think..). No Big-O places in UK to go get a replacement. They sent me a chq for all 3 and ended up buying BFG's (as no Big O's!)
 
Tools R Us said:
When I first got my Nitto's (295 A/T) I ran 40 psi, they wore in the center, crowned and the side tread blocks were barely touching the ground. Did the chalk test and it showed the best pressure to be 32 psi for even contact. I run 30 psi around town and 35 psi on trips.

The ideal pressure depends on vehicle weight, rim width, average speed, temperature, tire type and construction, etc. Slightly under inflated tires wear the outside of the tread, provide more traction, increase roll/sway, increase ride comfort and take more fuel/power to turn. Over inflated tires wear the center of the tread, provide less traction, decrease roll/sway, ride like $&!* and take less fuel/power to turn.
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Don't forget that your Nitto is a 123 load capacity of 3400 pounds at 65psi, so its load capacity inflation table is going to look different than a 119 tire rated for 3000 pounds at the same pressure.
 
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