BFG KO2 LT275/70R17 - Tire Pressure Info

[BButah]

For anyone running this tire....
I thought I'd post my experience as a point-of-reference.

When I bought my truck, I put these tires on the stock sport wheels. I had a local off-road specialist mount the tires when they installed my level kit. They set all 4 tires at 40psi.

I did a bunch of reading online and watching the forums on tire pressure and found everything "from A to Z" = 32-60psi! Over the winter, I set my tires at 38psi with the intent on "chalking" them when it warmed up.

I finally got around to the chalking process; so I thought I'd share what I found.

First off.... I headed over to Michael's Crafts for some YUGE "sidewalk chalk":

I aired up my tires to 42psi and headed to a local parking lot where I could get a clear & straight minimum 100' run. I over inflated as it's easy to let air out, but I do have a 12V air compressor in my on-board tool kit if I needed more air.

I used the side of the yellow chalk stick and colored about 4-5" across the tread: making sure to go all the way to the inside/outside edges:

I did this to each tire, and then slowly drove straight for approximately 100'. I stopped and made sure the chalked area was in view on each tire.

This first attempt at 42psi showed most of the chalk was off the tread in the middle of the tire, but the outer 1" or so on the fronts and a little more on the rears still had some chalk. (at this point I will add my truck has no load, and I don't plan to drive it loaded, but if I did, I would adjust the tire pressure accordingly.)

I dropped the fronts down to 40psi and the rear to 39psi, re-chalked and repeated the process. There was still some chalk on both the inside & outside tread on the fronts, and again a bit more on the rears.

In the end, I have decided based on my set up and these results, to set my tire pressure at 39psi in the front & 37psi in the rear.

I can't really tell a difference in the ride vs. my original 38psi set up. For me, this exercise was more of a "confirmation" of the proper psi and an attempt to set the tires up with a pressure for optimal wear.

Hopefully that is the case and maybe this can help others to set their pressure as well.

Cheers!
?

Sponsored

 

[Dhass68]

On a 10 ply tire you do need to keep a little higher air pressure than the stock 4 ply to help it to run cooler

 

[Desert_5G]

For anyone running this tire....
I thought I'd post my experience as a point-of-reference.

When I bought my truck, I put these tires on the stock sport wheels. I had a local off-road specialist mount the tires when they installed my level kit. They set all 4 tires at 40psi.

I did a bunch of reading online and watching the forums on tire pressure and found everything "from A to Z" = 32-60psi! Over the winter, I set my tires at 38psi with the intent on "chalking" them when it warmed up.

I finally got around to the chalking process; so I thought I'd share what I found.

First off.... I headed over to Michael's Crafts for some YUGE "sidewalk chalk":

I aired up my tires to 42psi and headed to a local parking lot where I could get a clear & straight minimum 100' run. I over inflated as it's easy to let air out, but I do have a 12V air compressor in my on-board tool kit if I needed more air.

I used the side of the yellow chalk stick and colored about 4-5" across the tread: making sure to go all the way to the inside/outside edges:

I did this to each tire, and then slowly drove straight for approximately 100'. I stopped and made sure the chalked area was in view on each tire.

This first attempt at 42psi showed most of the chalk was off the tread in the middle of the tire, but the outer 1" or so on the fronts and a little more on the rears still had some chalk. (at this point I will add my truck has no load, and I don't plan to drive it loaded, but if I did, I would adjust the tire pressure accordingly.)

I dropped the fronts down to 40psi and the rear to 39psi, re-chalked and repeated the process. There was still some chalk on both the inside & outside tread on the fronts, and again a bit more on the rears.

In the end, I have decided based on my set up and these results, to set my tire pressure at 39psi in the front & 37psi in the rear.

I can't really tell a difference in the ride vs. my original 38psi set up. For me, this exercise was more of a "confirmation" of the proper psi and an attempt to set the tires up with a pressure for optimal wear.

Hopefully that is the case and maybe this can help others to set their pressure as well.

Cheers!
?

I run mine at 34. No one should ever be filling their by going off what's on the tire. Even 40 psi is way to much.

 

[BButah]

On a 10 ply tire you do need to keep a little higher air pressure than the stock 4 ply to help it to run cooler

Hey Dan,

From your picture, I see you have the BFG KO2's.

Are you running the same size as mine? (LT275/70R17)

May I ask what pressure you run?

 

[NvrFinished]

Something to be aware of with BFG A/T tires as well as some other brands, is that the tire is designed to run more on the center lugs that cover approximately 3/4 of the cross section of the tread pattern. The more aggressive outer tread lugs are tapered slightly downwards on both edges if you look across the top of the tread pattern.

They design the tire this way in order to provide a quieter ride, better fuel economy, and quicker steering response. As soon as the tires run across any type of softer terrain, the center lugs sink in slightly and the larger outer lugs begin doing there job.

This is something that needs to be taken into consideration when doing the tire chalk test. You can easily end up with too low an air pressure if you are basing it solely on what the chalk is telling you near the edges of the tire.

 

[TylerV76]

Running the same size on the sport 17 wheels and I’ve kept mine at 38 during winter and so far this spring. I tried 32/34/36/40 and didn’t like it. 38 is the sweet spot for me.

If I’m going off road I drop them down depending where I’m going.

 

[BButah]

Something to be aware of with BFG A/T tires as well as some other brands, is that the tire is designed to run more on the center lugs that cover approximately 3/4 of the cross section of the tread pattern. The more aggressive outer tread lugs are tapered slightly downwards on both edges if you look across the top of the tread pattern.

They design the tire this way in order to provide a quieter ride, better fuel economy, and quicker steering response. As soon as the tires run across any type of softer terrain, the center lugs sink in slightly and the larger outer lugs begin doing there job.

This is something that needs to be taken into consideration when doing the tire chalk test. You can easily end up with too low an air pressure if you are basing it solely on what the chalk is telling you near the edges of the tire.

I was not aware of that design. I really like the ride in this psi range. I’m just trying to optimize wear, etc.

One thing I noticed was at highway speed after about 30 minutes, the tire monitors showed the pressure going up 4psi in the front and 3 psi in the rear.

I guess that’s another variable, eh?

 

[Dhass68]

I am running 40 all the way around and yes 275/70R17

 

[NvrFinished]

One thing I noticed was at highway speed after about 30 minutes, the tire monitors showed the pressure going up 4psi in the front and 3 psi in the rear.

I guess that’s another variable, eh?

Yes, tire pressures will increase with temperature. Conversely, they will decrease with cooler temps. It is another variable in the equation, however, don't put too much weight in those variables. Ride, wear, and overall performance based on initial temps is what it most important.

 

[Javier0419]

Hi I have the same tires and size. Had them for about two weeks. 500 miles with them:: I am using 37psi cold. Still not convinced and might play with them.. i would not mind a smoother ride overall.
thanks for all of the suggestions!

 

[OxyGenIII]

I have 285-70-17 ridge grapplers, C Load so 6 ply not 4 and not D rated 10 ply tires either.

Max psi on the sidwall is 51psi I believe. Tire shop installed them at 48 psi, rode like a brick. Lowered to 42 psi and it road better but still harsh. Finally settled on 38 front and rear as a hot hot summer day itll go up a psi or two. New alrignment and frequent rotations so ill keep track of tread wear but the contact patch looks flat and it rides great so I'm happy.

 

[P. A. Schilke]

I have 285-70-17 ridge grapplers, C Load so 6 ply not 4 and not D rated 10 ply tires either.

Max psi on the sidwall is 51psi I believe. Tire shop installed them at 48 psi, rode like a brick. Lowered to 42 psi and it road better but still harsh. Finally settled on 38 front and rear as a hot hot summer day itll go up a psi or two. New alrignment and frequent rotations so ill keep track of tread wear but the contact patch looks flat and it rides great so I'm happy.

Hi Folks,

Side wall is the max pressure for a particular tire. All Manufacturers of tires have load vs vehicle weight charts. Follow the recommend pressure for your vehicle weight for both curb and laden weights but do not exceed the tire sidewall. Your tire installer should have these charts but if not, go to the manufacturer's web site and download this chart. This trial and error pressure set may result in poor tire wear.

When running prototypes on Durability, when laden, we inflate to the tire Mfg recommendations and when unladen, we deflate to the recommended pressures. We also test vehicle dynamics at the recommended pressures. When you mod your Ranger Tires, you are out of Ford's arena, but your tire manufacturer should be able to give you the pressures for your vehicle. That said. Get your vehicle weighed so you know its weight. I see so many trucks with diamond plate cross bed tool boxes loaded and tires woefully underinflated for the load of lead in the tool box. Knowledge and data and the information contained in this date are the key to success.

I retreat from my soap box to my flame proof bunker...

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

 

[OxyGenIII]

Hi Folks,

Side wall is the max pressure for a particular tire. All Manufacturers of tires have load vs vehicle weight charts. Follow the recommend pressure for your vehicle weight for both curb and laden weights but do not exceed the tire sidewall. Your tire installer should have these charts but if not, go to the manufacturer's web site and download this chart. This trial and error pressure set may result in poor tire wear.

When running prototypes on Durability, when laden, we inflate to the tire Mfg recommendations and when unladen, we deflate to the recommended pressures. We also test vehicle dynamics at the recommended pressures. When you mod your Ranger Tires, you are out of Ford's arena, but your tire manufacturer should be able to give you the pressures for your vehicle. That said. Get your vehicle weighed so you know its weight. I see so many trucks with diamond plate cross bed tool boxes loaded and tires woefully underinflated for the load of lead in the tool box. Knowledge and data and the information contained in this date are the key to success.

I retreat from my soap box to my flame proof bunker...

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

I have checked Nittos website and there is no information on plus sized tire pressures based on load or weight.

 

[P. A. Schilke]

I have checked Nittos website and there is no information on plus sized tire pressures based on load or weight.

Sad it is not readily available...I think you need to dig deeper, give then a call in need be.

 

[JetEngr19]

I have checked Nittos website and there is no information on plus sized tire pressures based on load or weight.

Here is the info for Firestone tires that I used years ago when changing to LT tires on an off-road build. It may be different than Nitto, but should give you an idea of what is involved to get a proper tire pressure.

Sponsored