BFG A/T KO2 Load Range E: what psi for towing?

[profdant139]

So here is the backstory -- I drive a nice little Tacoma v6 4x4, and I tow a little 2500 lb. trailer. So why did I just buy a set of massive BF Goodrich All Terrain KO2 in Load Range E (LT 265/75R16)? I'm glad you asked!

Here's why -- we often boondock in places that seem to specialize in very sharp rocks. (The Sierra, the Cascades, the Wasatch range, the Rockies . . . very pointy places.) Originally, I rejected the Rugged Trails that came with the Tacoma, and the dealer put on Rugged Terrains, which were ok. But when we recently got a puncture right in the middle of the tread while gently off-roading (I don't go over 20 mph off road), I said, "That's it. Give me tank treads." (We changed the flat ourselves, and it was kind of fun, but it took us a long, long time to do it right and to do it safely. Not a good use of our limited recreational time.)

I am quite sure that my mpg will take a hit from these new tires, and that they will be noisier than my old tires. I am happy to live with those effects, if the 10-ply tires will reduce the chance of an inconvenient flat. Plus we do enough mud, snow, ice, gravel, and sand driving to justify the knobby tread. (I don't care how funny they look on my little truck, like big hiking boots on a skinny little boy -- these tires are not for show.)

The PSI recommendations on the doorframe are for the stock tires, which is meaningless with these new monster tires. And the BFG website is also useless, surprisingly. I did the usual Googling, with partial success. I learned about the "chalk" test, which I used to figure out my everyday PSI -- I took a yellow crayon, drew a line across the tread of all four tires, drove for a hundred yards, and determined that I had overinflated the tires (at 60 psi) because the crayon wore out in the center of the tire before the sides. At 50 psi, the lines wore out uniformly. This test took me about an hour of trial and error, slowly cruising up and down my block -- the neighbors must think I am going crazy. For everyday driving, I'm going with 50 on the front and 55 on the rear, since the door sticker had a 3 pound difference for the stock tires, and these are substantially beefier than the original equipment.

I suppose I could hitch up the trailer and do the same test while towing, and I probably will have to do that at some point. But I am hoping that someone else has already figured this out and can save me the trouble! And while you are calculating the proper PSI, I assume that the front and the rear will be different, but by how much? (By the way, the max PSI under full load is 80.) I am guessing 75 psi in back and 65 in front, but those are just guesses.

Thanks in advance for your advice!!

(PS -- dear moderator, if this should be in "tow vehicles" rather than "towing," please feel free to move it. I took my best guess -- it looks like more tire discussions end up in towing than in tow vehicles.)

[profdant139]

Great info, folks -- thanks! And this Tacoma came with Bilsteins, but I don't know which model number -- I will check. It is good to know that I do not have to air up for towing -- that will make for a much more comfortable trip.

[gmw_photos]

profdant139 wrote:
gmw, am I reading that right? You put more air in the front than the rear when towing? I guess I had it backwards!

And you are right that I am not coming anywhere near the load limit on those tires, so I guess I can back down from my high pressure settings. I don't want to run the tires so low, however, that the sidewall flexes and heats up the tire during normal highway driving.

And on the third hand, more psi equates to better mileage, but too much psi will cause wear on the centers of the tread.

Yes, Dan you read that right. I hesitated to use the dually as an example, because the fact there are four tires in the rear makes it an apples to oranges comparison, and can sometimes just confuse the discussion. But that's the way it works....with four in the back to carry the load, and only two in the front, the pressures need to be lower back, higher front.

In your case, the added puncture resistance you will get with your new tires compared to your old ones is going to come from the much more robust construction. Compare the weight of your new tires to what your old tires were ( the weight will be on the BFG site or the tirerack site ). You'll see a major difference.

Also, go back to my previous post re my Frontier with the FF hooked up, and you'll see that it weighs nearly the same front and rear when I am set up to go camp. As a consequence, I run the same pressure F/R on that little truck, since the loads are essentially the same. I experimented with higher pressure in the rear tires of the Frontier, but all it did was wear the center more, so it was clearly too much.

Here's a suggestion: since your new tires are heavier, that means more unsprung weight. This may cause you to notice any deficiencies in the shocks, especially at speeds over about 40 mph. If you have not already done so, I would recco Bilstein 5100's for it. They are about the stiffest damped shock you can get for it.

[dodge_guy]

I think everyone answered your towing questions.

Now, Do you air the tires down when on the sharp rocks? That will minimize damage to the tire!

[Grit_dog]

I wouldn't even be thinking about 50 psi + with those tires and a little trailer.
In my 8000lb (empty) diesel I run about 55F/45R in the summer. Winter may lower all around by 5-10psi from that depending on conditions (snow/ice/how much/ how cold).
I hook up a 6000lb trailer with considerably more tongue weight in the summer with 45-50 psi rear.
I'd start with the same pressure you were running with the P tires before.
quick guess, 35F/30R empty and bump up the rear 5-10 psi with a load.

[rhagfo]

gmw photos wrote:
Dan, I would suggest doing some reading on the off road forums. I think you'll find that most of the guys will say that somewhat lower pressures will help you avoid rock punctures.

EDIT: My feeling is there is no situation, at all, for those tires on that truck where you would run 80 psi. Or even 60 to 70. The truck just can't carry that much load ( weight ).
I also have a F350 dually with load range E ( 80 psi max ) tires, and even with the 14K pound horse trailer on the back, I don't run 80 psi ( but, it's got four tires in the back, but still, there is more weight on the back axle alone than what your Tacoma, or my Frontier weighs in total. I'm usually at 5600 to 5800 on the rear axle ) And at that I run 60 in the rears and 70 in the fronts.

profdant139 wrote:
gmw, am I reading that right? You put more air in the front than the rear when towing? I guess I had it backwards!

And you are right that I am not coming anywhere near the load limit on those tires, so I guess I can back down from my high pressure settings. I don't want to run the tires so low, however, that the sidewall flexes and heats up the tire during normal highway driving.

And on the third hand, more psi equates to better mileage, but too much psi will cause wear on the centers of the tread.

Well four tires carrying 5,800# is 1,450# per tire!! about half of the tires 80 psi capacity. the front is likely close to 4,500# which is about 2,250# per tire closed to the tires capacity.

Those that run 80 psi in DRW TV, and complain about ride should hit a scale loaded and unloaded and adjust tire pressure according.
I don't run 80 psi in my SRW 2500 at 5,500# on the rear axle usually about 65 psi, then 45 to 50 psi unloaded. It is about traction and ride!!!

[profdant139]

gmw, am I reading that right? You put more air in the front than the rear when towing? I guess I had it backwards!

And you are right that I am not coming anywhere near the load limit on those tires, so I guess I can back down from my high pressure settings. I don't want to run the tires so low, however, that the sidewall flexes and heats up the tire during normal highway driving.

And on the third hand, more psi equates to better mileage, but too much psi will cause wear on the centers of the tread.

[gmw_photos]

Dan, I would suggest doing some reading on the off road forums. I think you'll find that most of the guys will say that somewhat lower pressures will help you avoid rock punctures.

EDIT: My feeling is there is no situation, at all, for those tires on that truck where you would run 80 psi. Or even 60 to 70. The truck just can't carry that much load ( weight ).
I also have a F350 dually with load range E ( 80 psi max ) tires, and even with the 14K pound horse trailer on the back, I don't run 80 psi ( but, it's got four tires in the back, but still, there is more weight on the back axle alone than what your Tacoma, or my Frontier weighs in total. I'm usually at 5600 to 5800 on the rear axle ) And at that I run 60 in the rears and 70 in the fronts.

[rhagfo]

profdant139 wrote:
rhagfo, you said something interesting about sharp rocks and pressure -- I have heard of airing down for sand and mud, but is that true of rocks, too?? Pardon my ignorance.

Had a neighbor who ran log trucks, roads are "Ballast Rock" big sharp stuff he ran his truck tires at 90 psi, not the 110 psi standard, tires lasted a lot longer, and I don't recall him ever throwing a tread, far fewer rock cuts to the tread.

[profdant139]

rhagfo, you said something interesting about sharp rocks and pressure -- I have heard of airing down for sand and mud, but is that true of rocks, too?? Pardon my ignorance.

[gmw_photos]

Hey Dan, I'm with the others regarding inflation. I think you're going to find you'll be running 38 to 40 maybe. My Frontier with my funfinder hooked to it has 2760 on the drive axle, and 2640 on the steer axle. You're likely a little lighter than I am. You're not going to need big pressure numbers. Higher pressure is for more load capacity.

[rhagfo]

Old-Biscuit wrote:
With that 2500# trailer (tongue weight of what------300#?)
I would just run 50 psi front and 55 psi rear all the time.

It's not like you are piling on huge weight increase from non-towing to towing!

Those tires likely have a 3,415 load rating at 80 psi, how much do you weigh on your rear axle?? Maybe 2,550# likely less.

With sharp rocks where you boondock I would think 45 to 50 psi, and that is likely too much!

[blt2ski]

Rear may need 10-15 lbs more, at most. Fronts probably nothing at all.

marty

[Old-Biscuit]

With that 2500# trailer (tongue weight of what------300#?)
I would just run 50 psi front and 55 psi rear all the time.

It's not like you are piling on huge weight increase from non-towing to towing!