BFG KM3 Review

Over the past 20 years I have owned or driven on every version of BFGoodrich Mud tires, so when I heard that there was an “All New” BFG KM3 coming out I was both interested and sceptical, as BFG has a reputation for small changes not huge leaps.   BFG has always made a good “Street Friendly” mud tire.  Not as good in mud or rocks as a more dedicated mud tire, but quieter and better handling on the street than the tires that outperform it off road.  When I got the KM3s I had a set of KM2s that I had been using for just under a year, so a big part of my focus on this review is whether the KM3 really is a big improvement.

It is important to note that as I still had my KM2s and was under no obligation to BFG this is a completely unbiased review.  If I didn't like the KM3s I would have simply gone back to my KM2s.

The testing was done using a set of 33x10.5” R15 tires mounted on 15x7 aluminum rims, which is exactly the same setup I had with my KM2s.  The test vehicles were a 97 Jeep TJ, a 2003 Jeep TJ Rubicon, and a 2005 Jeep LJ.   When the tires were mounted by Ken at Symon’s tire in Mission he found that the tires popped on the rims so easily that he did not even need to remove the valve cores to mount them, which is good news for those concerned about being able to reseat a bead on the trail.  In addition they are very close to perfectly round and straight so they balanced with very little weight.

Comparing the  new KM3 you see that that the sidewall has far larger and deeper side biters that extend much further down the tire than on the KM2.  What isn’t so obvious is that the sidewall has been redesigned internally as well.

KM2 on the left, KM3 on the right

The KM2 tires have a thin area that can be seen and felt from inside the tire, roughly corresponding to where the Mud Terrain lettering is on the outside of the tire, and they have a reputation for getting cut in this area.  The sidewall on the KM3 on the other hand, is uniformly thick.  BFG claims a 27% increase in sidewall strength, and I have no problem believing that claim.

Km2 with thin area marked


Of course the next question is whether that new thicker sidewall will flex well. The answer is unequivocally yes.  In fact at low pressures the KM3 flexes better than any other radial tire I have owned, with minimal cupping to the tread and with the side biters flattening out on the ground to give more traction.  At 8 PSI my 10.5” wide tires effectively act like 12.5” wide tires due to the way they flatten, yet I routinely run on dirt roads at 50 kph at that pressure and have never lost a bead (I do slow for sharp corners).

The tread on the KM3 has also been redesigned.  It’s not radically different, however there are now more channels for evacuating water and mud, larger suction breaking bars between the tread blocks to prevent mud from packing in, rock ejector knobs in the largest gaps, and the tread blocks themselves are slightly larger overall.  Despite this I have not noticed any increase in road noise compared to the KM2.  Personally I would have liked to have seen BFG also add a bit of siping to the KM3 tread for better winter traction, however it does have a Mud and Snow rating so you shouldn’t have issues with being turned away at a checkpoint on a mountain highway.

Km2 Vs Km3

In addition BFG has modified the rubber compound itself, giving, according to their press release, 8% better traction on rock.   It will, of course, be a while before we know exactly how the new compound affects the longevity of the tires, however BFG has said to expect slightly faster wear than the KM2.  With 6,000 kms on my set they only show slightly more wear than my KM2s did.

On rocks the KM3s definitely live up to the hype, especially in situations where you can bring the new side-biters into play.  There is one Rock Garden that I routinely play in that has a large ledge on one side as you enter.  On my KM2s I had tried and failed a couple of times to angle up onto that ledge, however the side of the back tire would never grip the rock and I would end up getting spun straight into the ledge, unable to go forward or backward due to clearance.   On the KM3s I cruise over that ledge like it isn’t there.   I have tested the KM3s on loose round rock, sharp shale, volcanic rock, rough granite, smooth granite, and sandstone.  In every case the KM3s performed better than the KM2s did, and despite driving on a lot of sharp rock at 8psi I have only cosmetic damage to the sidewalls.

In mud I honestly did not see a change between the KM2 and KM3.  I even went so far as to put KM2s on one side and KM3s on the other to see if there was a difference in how well they clear mud from the tread, but I found that they either both cleared or both clogged up.  I can see that the side biters would help you pull up out of ruts, and in theory the tread should clean better, but in the limited testing I did there wasn’t a notable difference.  That’s not to say the KM3s are bad in mud – for a street friendly mud tire they do quite well, just don’t expect the performance you would get from a more aggressive mud tire.

On dirt and loose gravel the ability of the KM3s to flatten out and bring the side-biters into play gives them even more traction than I expected, and has allowed me to climb hills that I really had no business going up in a near-stock rig with open diffs.  At the Pacific North West Jamboree we ran with a pack of locked Jeeps on trails that are rated “Most Difficult” and took on every obstacle offered without any traction issues.

The highway manners are good for a mud tire, and I actually found the tires chirping while braking on wet pavement.  I did end up running at 35 psi on road vs the 32 psi I ran in my KM2s as I was finding the edges of the tread were rolling a bit under hard cornering.   I will be adding siping to the tread for winter driving, but that’s nothing new for me as I find most tires can benefit from some additional siping.

Overall I am very happy with the new KM3s.  BFG addressed the complaints some people had about the KM2 sidewalls and they evolved nearly every aspect of the tire, putting them right back to their usual position as one of the top tire choices for people who need both good street manners and great off road traction.