BF Goodrich - KM3's - Info and opinions needed

[spaggyroe]

I'm contemplating a set of 35x12.50 BFG KM3's. I thought I'd ask if anyone is currently running them and if so, what is your impression of them?

I'd also like to know how true they measure out to be. The KM2's apparently measured quite small compared to their advertised size.

Thanks!

 

[Greg]

I'm running 37" KM3's on the Gladiator and have been quite happy with them. I've got around 8k miles on them now and they're getting a little 'hum' to them going down the road, but I don't mind it at all. Offroad in Moab they're awesome, big chunky lugs that work hard to maintain traction. In the snow and ice they're not as good as an AT, obviously. I think they have great road manners and run down the freeway just fine.

I haven't measured my 37's recently, but they're probably right around 35 1/2" to 36" diameter. I wouldn't be surprised if the 35" KM3 measured out to 33 1/2 to 34" or somewhere in there. I think BFG's truck tires all tend to run smaller than advertised size, other than Krawlers.

 

[Medsker]

I'm running 37's on my Jeep JL as well. I've been running BFGoodrich mud terrains for years and have always been impressed by them. I had the middle lugs of mine siped so it would do better on the ice over the winter. I think it helped a lot but it did make them a lot louder. I have over 25,000 miles on mine and they still have a lot of tread left on them. I think Greg's right they do run smaller than the listed size. I don't think you can go wrong with them.

 

[Stephen]

I've got a set of 255/75/17's on my Trooper, only put 1,000 miles on them or so since I bought them. They do make a fair amount more noise than the old KM's on the freeway, but not horrible by any means. So far, I've been pretty impressed with the traction in loose gravel and mud. Haven't had a chance to do any "crawling" with them yet, but being BFG, I'm sure they'll do the job.
Oh, and they look much more aggressive. That's the most important part!

 

[Kevin B.]

I think BFG's truck tires all tend to run smaller than advertised size

BFG says 34.6 for the 315/75r16. You think that's generous?

 

[spaggyroe]

I found this chart online

BFGoodrich Mud-Terrain T/A KM3 Tires

BFGoodrich Mud-Terrain T/A KM3 tire specs. Find specs for BFGoodrich Mud-Terrain T/A KM3 tires in every size available on the market.

tiresize.com

It lists the 35x12.5 R17 KM3 as having a 34.5" diameter

I also found this site

BFG KM3 Mud T/A First Impressions.

BF Goodrich has just released the new Mud Terrain KM3 and the off-road world is excited to see what the changes are. BFG KM2s are already known for being tough and giving excellent traction in many different types of terrain. The question that you may ask… Why is everyone so excited over the new...

www.northridgenation.com

.
They measured one (unmounted) at 34-1/16"

I'd love to see one physically measured that has been mounted.

 

[DAA]

I could measure one - the only one I have. But it is on the Jeep, which of course will effect the measurement. They do run small.

- DAA

 

[DAA]

Okay, sample of one (the rest of my tires are KM2's). 35x12.50-17, mounted on an 8.5" wheel, at 34 psi, with 12/32 of tread left, on the passenger front of my LJ.

33-3/4"

- DAA

 

[spaggyroe]

Okay, sample of one (the rest of my tires are KM2's). 35x12.50-17, mounted on an 8.5" wheel, at 34 psi, with 12/32 of tread left, on the passenger front of my LJ.

33-3/4"

- DAA

Thank you sir!!

 

[Kevin B.]

Okay, sample of one (the rest of my tires are KM2's). 35x12.50-17, mounted on an 8.5" wheel, at 34 psi, with 12/32 of tread left, on the passenger front of my LJ.

33-3/4"

- DAA

^ 18/32s when new is what BFG says. That's nowhere near 34.6, more like a clean 34.

And that just makes me mad. Why you gotta be like that, BFG?

 

[spaggyroe]

I have some KM2’s on my camping trailer (cause who doesn’t need that), and they measure out at 34”

 

[RockChucker]

I’ve heard that the tire size is a dynamic measurement at 65mph. But I’ve never been able to find anywhere in a paper or article supporting that...

I’ve got “39” km3s. But they are slightly less than 38”. Much smaller than my 40” kr3s that are true to size. That said, they work pretty well. Granted every tire works well in Moab. But I think they work better than the maxxis razrs I replaced with these.

 

[I Lean]

I’ve heard that the tire size is a dynamic measurement at 65mph. But I’ve never been able to find anywhere in a paper or article supporting that...

@BlackSheep might be able to shed some light on this?

 

[Shawn]

I run 37 KM3’s on my JL, good tire, killer in snow/mud. Really haven’t been on rock yet, but I like these tires.

 

[cruiseroutfit]

I’ve had some on a little Land Cruiser for 4-1/2 years now? They have been great. I pulled a nearly new set of KM2’s off. The KM3’s we’re quieter and have held up really well.



John and Ben at Impulse Offroad are the go-to’s for them locally. I picked up a set of 35’s for my FJ40 from them last year. They have been great on the 40 too.

 

[BlackSheep]

@BlackSheep might be able to shed some light on this?

The measurements listed in the tire specifications are typically done with a tire mounted on the Measuring Rim and inflated to maximum pressure. The dimensional notations (i.e. 35x12.50R17LT) are defined by an industry standard organization called the Tire and Rim Association (TRA). There are counterpart organizations in other countries - Europe has the European Tyre and Rim Technical Organization (ETRTO) and there are others. These organizations publish annual yearbooks that specify details about the tire size. Their purpose is to allow the OE manufacturer to design the appropriate size wheel well and to provide the end user (that's us) a reasonable expectation that a tire of a given dimension will be similarly sized regardless of tire manufacturer.

There is actually a design window specified by these industry standard organizations (TRA, ETRTO, etc). It is a plot where the horizontal axis is the section width (SW) while the vertical axis is the overall diameter (OD). I tried to find an example but couldn't turn one up in the limited searching I did online. What it means when I say 'window' - the TRA specifies a minimum and maximum value for both SW and OD for a given dimension. As long as the tire manufacturer puts the tire in the window they are abiding by the standard. I'll try to find an example of this later.

The OD measurement is taken in the center of the tread - it's actually a circumference that is being measured, then converted to the diameter. If you mount your tire on your vehicle and measure the height, you'll be sorely disappointed when you see that your tire doesn't measure up to even the spec listed on the spec sheet. Of course that's because under load the tire will deflect. Although not typically published for passenger car tires, in the Truck tire world we often publish the static loaded radius (SLR) - that's the distance from the ground to the center of the tire when the tire is mounted, inflated to max pressure, and loaded to max load. Note that 2 x the SLR is NOT equal to the tire height on your vehicle.

If you mount your tire on a rim that is not the same as the measuring rim, you can also expect to see some variation in OD and SW. Narrower rim will result in a narrower and taller tire while a wider rim will result in a wider and shorter tire.

Hope that sheds some light on the measurement situation. I'll try to find an example of the design window.

 

[Kevin B.]

I’ve had some on a little Land Cruiser for 4-1/2 years now? They have been great. I pulled a nearly new set of KM2’s off. The KM3’s we’re quieter and have held up really well.

View attachment 128191

John and Ben at Impulse Offroad are the go-to’s for them locally. I picked up a set of 35’s for my FJ40 from them last year. They have been great on the 40 too.

You were (are?) running the X3s on the 200, weren't you? How do they compare in your opinion?

 

[bryson]

View attachment 128192
The measurements listed in the tire specifications are typically done with a tire mounted on the Measuring Rim and inflated to maximum pressure. The dimensional notations (i.e. 35x12.50R17LT) are defined by an industry standard organization called the Tire and Rim Association (TRA). There are counterpart organizations in other countries - Europe has the European Tyre and Rim Technical Organization (ETRTO) and there are others. These organizations publish annual yearbooks that specify details about the tire size. Their purpose is to allow the OE manufacturer to design the appropriate size wheel well and to provide the end user (that's us) a reasonable expectation that a tire of a given dimension will be similarly sized regardless of tire manufacturer.

There is actually a design window specified by these industry standard organizations (TRA, ETRTO, etc). It is a plot where the horizontal axis is the section width (SW) while the vertical axis is the overall diameter (OD). I tried to find an example but couldn't turn one up in the limited searching I did online. What it means when I say 'window' - the TRA specifies a minimum and maximum value for both SW and OD for a given dimension. As long as the tire manufacturer puts the tire in the window they are abiding by the standard. I'll try to find an example of this later.

The OD measurement is taken in the center of the tread - it's actually a circumference that is being measured, then converted to the diameter. If you mount your tire on your vehicle and measure the height, you'll be sorely disappointed when you see that your tire doesn't measure up to even the spec listed on the spec sheet. Of course that's because under load the tire will deflect. Although not typically published for passenger car tires, in the Truck tire world we often publish the static loaded radius (SLR) - that's the distance from the ground to the center of the tire when the tire is mounted, inflated to max pressure, and loaded to max load. Note that 2 x the SLR is NOT equal to the tire height on your vehicle.

If you mount your tire on a rim that is not the same as the measuring rim, you can also expect to see some variation in OD and SW. Narrower rim will result in a narrower and taller tire while a wider rim will result in a wider and shorter tire.

Hope that sheds some light on the measurement situation. I'll try to find an example of the design window.

Interesting info. Is there a reason why BFG's specifically are (nearly always) smaller when compared to a identically labelled tire from a different manufacturer? I assume they are still in the "window" you mentioned for that size designation, but why always at the low end of the range?

 

[RockChucker]

Interesting info. Is there a reason why BFG's specifically are (nearly always) smaller when compared to a identically labelled tire from a different manufacturer? I assume they are still in the "window" you mentioned for that size designation, but why always at the low end of the range?

@BlackSheep very interesting. I would 2nd what Bryson said above about bfg’s always running on the smaller side.

 

[moab_cj5]

Is there a reason why BFG's specifically are (nearly always) smaller when compared to a identically labelled tire from a different manufacturer? I assume they are still in the "window" you mentioned for that size designation, but why always at the low end of the range?

I am a BFG Fan, but also a capitalist theorist. I suspect they make them smaller so you are willing to buy the next size up for a price premium to get the size you really want...🤷‍♂️

When I go to put 37's on my cruiser, I will be looking at 37's from most manufacturers, but 39's from BFG and paying a premium for the 39's...