BFG KM2 tires

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AHTOXA
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BFG KM2 tires

Post by AHTOXA » Mon May 30, 2011 9:33 pm

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When I started modifying the Rubicon, I knew that tires would be key. All the modifications that have been done were done to primarily fit the needed size tire under the truck. A bigger tire helps get over obstacles more easily. As always, there's a point where this becomes a diminishing return and handling, braking, steering and acceleration are going to be affected by the tire size and subsequently the weight. Granted, there are always mods to counter the balance, but this isn't the place for that discussion.

I chose a size of 33x12.5x15. Since the Rubicon is daily-driven, I didn't want to entirely toss the handling aspect out of the window; that and bigger tires are also more money (in gas, needed supporting mods and tires themselves). These have been driven on street and offroad and I can speak to the performance of these as related to this rig and other mud tires I have run in the past on a different vehicle. Let's get down to business and I'll quit getting off topic.

Deep mud: 8/10

There are different types of mud. Some is more runny, earthy and there's brownish clay-like mud. Clay-like mud is the worst in terms of coating your tires, filling your lugs and essentially turning your tire into a slick no matter how hard you try to spin them to clean the treads. Here were generally have the regular earthy mud, which isn't as bad. These tires performed admirably as expected. The tread self-cleaned well. The blocks are spaced out far enough to be able to accompliush that. Grab is good even when there are hidden slippery roots under the mud. These tires only yield to dedicated mud tires like Super Swamper Boggers and similar. I'm also not counting paddle wheels and the like.

Sand (dry/wet and deep) 6/10

This was also predictable. Mud tires aren't the best in sand. Sand is all about flotation. You don't want to start digging into it. Generally All Terrain tires perform better in sand due to less agressive tread and more flotation when placed in sand. As with any mud tire, you want to keep momentum up in the sand and avoid putting down excessive torque.

Rocks (wet and dry) 9/10

This is where this tire shines. I've run Goodyear MT/Rs before and Kumho MTs and I feel that these are superior. The tread for these tires was developed based on BFG's Krawler tire of the rock-specific stock. The KM2's worked great in all conditions. Wet, slippery rocks can be tricky but this tire handled well. When I first took them out to play, I began testing to see what pressure they run best at. Different tires can vary somewhat in regards to how much pressure is needed for them to work at their ultimate. It all depends on weight of the vehicle, tire's load rating, sidewall and tread design as well as compound itself. There's no general answer for any specific tire. You have to get out and try it.

I started at 18 psi and was perplexed when I was in the rock garden with front and rear locked and I was having a hard time. Progress was slow and I was slipping more than I should have. Granted the conditions were challeging due to all rocks being wet, however I've gone through this particular garden many times before in a open-diff vehicled, no lockers and IFS front end. It was obvious further airing down is needed. I dropped down to 13psi and walked right out of the garden. Later I have gone down to 12 and wheeled it at that for the rest of the day. At that pressure the lugs were working nicely. They would wrap and literally adhere to anything I have wheeled that day. Laterall stability was good, only expected slipping in off-camber situations, depending on terrain.

Fact of the matter is, this tire and wheel combination is capable if running 7-9 psi in the rocks without popping a bead (if driven smartly). I've never gone down to single digits in any of my tires as blowing a bead on the trail just holds everyone up.

Street 6/10

This tire performs well on the street. You need to be aware of what vehicle you're driving and what tires are on there. Common sense stuff here, folks. I gave it a slightly above average rating because they seem to be fairly quiet on the street (for what they are). I will know more in about 10k miles when they wear down a little. As MT tires wear, they become profoundly noisier. Wet grip is good. Dry grip is fine, although I have not nearly pushed either. Hydropaning resistance is excellent. We have had torrential downpours here last week and they performed well in deep standing water at speed. This is mainly attributed to deep lugs, which makes a lot of channels for the water to escape. I can't comment on wear at this time but I expect 40-50k miles out of these.

Price 5/10

These guys aren't cheap. 33x12.5x15 run at $212 a piece at tirerack, which is where I got them from. There are some cheaper tires out there that don't perform as well and there are more expensive ones that are truly dedicated rock tires or mud tires or what not. This price is just that - quite average for this market.

FOSE: wear your rubbers, boys, and every little thing is gonna be alright.
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Re: BFG KM2 tires

Post by Shadow » Tue May 31, 2011 8:08 am

Some of the guys on the 4Runner forum run those tires. Most seem pretty happy with them. Personally, I avoid M/T tires because I don't spend much time in mud. In fact, most of my driving offroad seems to be during the winter months, so I'm more likely to be in snow than mud.
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Re: BFG KM2 tires

Post by AHTOXA » Tue May 31, 2011 9:14 am

Deep snow is an MT tire territory and so are rocks. Offroad I primarily play in the rocks and don't like mud.
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Re: BFG KM2 tires

Post by Shadow » Tue May 31, 2011 9:26 am

AHTOXA wrote:Deep snow is an MT tire territory and so are rocks. Offroad I primarily play in the rocks and don't like mud.
M/T tires don't have enough siping to be effective for most snow conditions. I've found that A/T tires work much better. And in deep snow, I'd rather not dig in, but rather try to "float" on top.
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Re: BFG KM2 tires

Post by AHTOXA » Tue May 31, 2011 9:44 am

It is true regarding light snow. MT tires' lugs are often too big and too smooth lacking sipes. I used to run BFG AT KOs for a while and then switched to MT for better traction off road. I had the MTs siped in the middle tread blocks and didn't have any issues in packed or light snow.

For deep snow you want to dig through it rather than float. Sand requires being able to float but not snow. Think of rally cars on snow tires. Those tires are hellishly skinny and studded. For optimal snow driving you always want to have the skinniest tire possible. It digs down to more solid ground and it's also more stable and has less tendency to pull the vehicle due to lesser surface area when you encounter snow drifts or are crossing snow ruts when changing lanes.

Deep, fresh snow will never be so dense for your tire to float on it, unlike sand. Even wet, heavy snow is simply not dense enough. Digging through it is the only option.
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Re: BFG KM2 tires

Post by AHTOXA » Tue May 31, 2011 9:46 am

Bottom line is, sipe an MT tire and it will do well in light snow. Deep snow, and it dominates.
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Re: BFG KM2 tires

Post by Shadow » Tue May 31, 2011 10:48 am

AHTOXA wrote:It is true regarding light snow. MT tires' lugs are often too big and too smooth lacking sipes. I used to run BFG AT KOs for a while and then switched to MT for better traction off road. I had the MTs siped in the middle tread blocks and didn't have any issues in packed or light snow.

For deep snow you want to dig through it rather than float. Sand requires being able to float but not snow. Think of rally cars on snow tires. Those tires are hellishly skinny and studded. For optimal snow driving you always want to have the skinniest tire possible. It digs down to more solid ground and it's also more stable and has less tendency to pull the vehicle due to lesser surface area when you encounter snow drifts or are crossing snow ruts when changing lanes.

Deep, fresh snow will never be so dense for your tire to float on it, unlike sand. Even wet, heavy snow is simply not dense enough. Digging through it is the only option.
Don't try to sell that story to these guys:

http://www.arctictrucks.com/pages/4700

Snow floatation can be very important. If I'm driving in snow piled on top of pavement, of course I want to dig down. The idea there is to reach the pavement and gain traction. But offroad, I don't want to dig into snow, especially deep snow. That's a good way to get stuck. My winter tires on my 4Runner are wide A/T tires with plenty of siping. It takes a lot of effort to get them dug down deep in most snow conditions.
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Re: BFG KM2 tires

Post by AHTOXA » Tue May 31, 2011 11:44 pm

True, but above you are talking extreme conditions. If those guys could get needed flotation with a smaller tire, so you think they wouldn't? Point is that with "normal" sized tires you simply cannot get the needed flotation in snow to be effective. I'm sure your tires aren't anywhere this big. Digging down is not an option in above example because that could be many, many feet. If your vehicle has clearance to dig down to the soil, then it's the best way there are no conditions here in the Midwest where normally accumulated snow is over 30 inches (outside of drifts). In these conditions I want the tires digging at the soil to propel me forward.

Extreme conditions aside, this has worked best for me.

Remember that I have used good ATs and MTs on the same vehicle for a number of winters and many offroad trips. I cannot argue with my results.
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Re: BFG KM2 tires

Post by Shadow » Wed Jun 01, 2011 8:11 am

AHTOXA wrote:True, but above you are talking extreme conditions. If those guys could get needed flotation with a smaller tire, so you think they wouldn't? Point is that with "normal" sized tires you simply cannot get the needed flotation in snow to be effective. I'm sure your tires aren't anywhere this big. Digging down is not an option in above example because that could be many, many feet. If your vehicle has clearance to dig down to the soil, then it's the best way there are no conditions here in the Midwest where normally accumulated snow is over 30 inches (outside of drifts). In these conditions I want the tires digging at the soil to propel me forward.

Extreme conditions aside, this has worked best for me.

Remember that I have used good ATs and MTs on the same vehicle for a number of winters and many offroad trips. I cannot argue with my results.
No, my tires aren't nearly that big. But the point is that floatation can be important on snow. It's not just extremely deep snow, either. If the snow is deep enough that your vehicle's chassis or suspension bottoms out before the tires can reach traction beneath the snow, then you simply don't want a tire that will "dig" into snow. That's the situation I face every winter wtih my 4Runner when I go up to our winter cabin near Syracuse, NY. Trust me, in those conditions I am much better off with an A/T tire (with lots of siping) that doesn't tend to dig down into the snow. Of course my tires will dig down a bit, but if they dig down too deep, I'm stuck when the snow is deep (and by deep, I'm only talking 18+ inches or so). When I look at my tracks after I get up the hill and to the cabin, there's nothing but compacted snow in the tire tracks.
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Re: BFG KM2 tires

Post by AHTOXA » Wed Jun 01, 2011 9:33 am

Well, we will agree to disagree.

My experience has been such that I far prefer a tire that can dig down into the snow. The widest AT I ran was 11.5 and I could not get any useful flotation out of it. While it may be possible, which I doubt, as soon as conditions changed and you needed the improved grip in deeper snow of a more aggressive tire, it simply won't be there with the AT.

It also comes down to technique. If its possible that you are floating you AT tire, then an MT can be floated just as well with careful throttle application. If your vehicle is stock, you aren't likely to have a tire wider than 10.5 inches. An MT will roll over and compact the snow as well, let's say. The deep spacing between the lugs creates pockets or blocks of compacted snow and as you may know, when the snow is deep, this provides the best grip since the snow sticks to itself well, conforming to the tire tread and providing a negative image of the tread for it to grip against.

So, given unobstructed forward momentum and conservative application of throttle which would limit tire spin, both tires are equal here but only when it comes to deeper snow. If, however, you forward momentum is suddenly impeded and you do need more forward momentum, you will start to dig. With an aggressive tire you can dig deeper, true, but if driven with common sense the added traction will propel you forward rather than digging too far down.
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Re: BFG KM2 tires

Post by Shadow » Wed Jun 01, 2011 12:35 pm

AHTOXA wrote:Well, we will agree to disagree.
I'm not disagreeing with you...I'm just telling you what works for me in the snowy conditions I usually encounter. I've had M/T tires as well as A/T tires and I've found the A/T tires work better for me.
My experience has been such that I far prefer a tire that can dig down into the snow. The widest AT I ran was 11.5 and I could not get any useful flotation out of it. While it may be possible, which I doubt, as soon as conditions changed and you needed the improved grip in deeper snow of a more aggressive tire, it simply won't be there with the AT.

It also comes down to technique. If its possible that you are floating you AT tire, then an MT can be floated just as well with careful throttle application. If your vehicle is stock, you aren't likely to have a tire wider than 10.5 inches. An MT will roll over and compact the snow as well, let's say. The deep spacing between the lugs creates pockets or blocks of compacted snow and as you may know, when the snow is deep, this provides the best grip since the snow sticks to itself well, conforming to the tire tread and providing a negative image of the tread for it to grip against.
Now here is where we disagree. A M/T tire is designed to clear mud (and of course that applies to snow as well) from the tread. Big block treads with big voids are obviously designed to clear itself out. And when it comes to snow traction, well, that's why siping is so important on snow tires. Yes, snow sticks to itself, so a lot of siping is always found on dedicated snow tires. A/T tires normally have much more siping than M/T tires. In fact, plenty of true M/T tires don't have much (if any) siping at all.

So, given unobstructed forward momentum and conservative application of throttle which would limit tire spin, both tires are equal here but only when it comes to deeper snow. If, however, you forward momentum is suddenly impeded and you do need more forward momentum, you will start to dig. With an aggressive tire you can dig deeper, true, but if driven with common sense the added traction will propel you forward rather than digging too far down.
No arguments there....other than the concept of not wanting to dig down in snow that will cause your chassis to bottom out. Because once that happens, you're basically screwed no matter what type of tire you're running. That's why I'd rather stay on top of the snow when I'm offroad in deep snow rather than digging into it. Again, that's just me.
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Re: BFG KM2 tires

Post by AHTOXA » Wed Jun 01, 2011 2:37 pm

You are incorrect here.

Siping is done to create a biting edge. When the rubber naturally flexes under the weight of the vehicle, the sipes open up to provide more contact area and to expose an edge to the snow, which provides traction. This principle is the same but method is slightly different from using snow adhesion to self and compression to provide a grip surface with a large lug tires.

Also, yes mud tires are designed to shed mud, however this only happens at certain speed of the tire and higher, depending on condition. Won't matter if you are driving very slow. Also, it doesn't happen as the tire is actually in contact with snow. Tread blocks conform and compact the snow using that for the lugs to push against and the wheel moves. Whether the snow is cleared from the tread once both are no longer in contact matters little in this case.
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Re: BFG KM2 tires

Post by Shadow » Wed Jun 01, 2011 2:48 pm

AHTOXA wrote:You are incorrect here.

Siping is done to create a biting edge. When the rubber naturally flexes under the weight of the vehicle, the sipes open up to provide more contact area and to expose an edge to the snow, which provides traction. This principle is the same but method is slightly different from using snow adhesion to self and compression to provide a grip surface with a large lug tires.
I never said anything to the contrary. I understand how and why siping works. Another benefit of siping is that it helps provide more surface area for the snow to "stick" to itself. Look at any snow tire as it is driven through fresh snow and the entire tread area will appear to be snow-covered.

Also, yes mud tires are designed to shed mud, however this only happens at certain speed of the tire and higher, depending on condition. Won't matter if you are driving very slow.
Once the tires lose traction and spin, a M/T will very easily shed snow it the tread blocks. That's great for digging into mud, but not so great when it makes your vehicle dig into deep snow. The problem here is that I'm talking about DEEP snow. You're obviously not.
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Re: BFG KM2 tires

Post by AHTOXA » Wed Jun 01, 2011 5:42 pm

Deep snow is a broad term. Regardless, my point is that if an AT tire can be floated, so can an MT with proper throttle application. However, if I need to dig at least somewhat, I'd rather have a more aggressive tire on because I can dig more efficiently and I dint have to sink all the way down.

There is a great video on YouTube where a buggy with 40s MT tires is digging through deep snow. He's not floating on it but digging with an aggressive tire with careful throttle. Slowly.I'll try to remember to look for it when I'm done with some mod installs tonight after work.

Snow like that cannot be floated on unless you are running a tire as big and as wide as those arctic trucks you posted. It's too powdery.
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Re: BFG KM2 tires

Post by Shadow » Wed Jun 01, 2011 8:32 pm

AHTOXA wrote:Deep snow is a broad term.
Exactly. That's why I said 18" and up earlier on in the thread. If I'm in deep snow, I don't want to dig.
Regardless, my point is that if an AT tire can be floated, so can an MT with proper throttle application. However, if I need to dig at least somewhat, I'd rather have a more aggressive tire on because I can dig more efficiently and I dint have to sink all the way down.
Yup, but again it totally depends upon the surface. I avoid digging in at all to get up to the winter cabin. It's not out of choice, it's simply necessity. Dig in and I'm done. Back to the bottom to try again. You may not find yourself in that type of situation.

There is a great video on YouTube where a buggy with 40s MT tires is digging through deep snow. He's not floating on it but digging with an aggressive tire with careful throttle. Slowly.I'll try to remember to look for it when I'm done with some mod installs tonight after work.
Post it if you find it. Sound interesting...

Snow like that cannot be floated on unless you are running a tire as big and as wide as those arctic trucks you posted. It's too powdery.
Keep in mind that you can still float on powdery snow because it tends to compact under the weight of your vehicle. So maybe you're not floating in a technical sense, but you're still not digging down to the harder surface (if there is one) under the snow. That's why I was trying to explain that my tracks leave nothing but compacted snow with no signs of dirt/mud/gravel showing on the surface. I'm able to move on top of the snow, without digging in deep at all.

Next winter I'll have to shoot a video for you to show you exactly what I'm talking about.
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