Hi everyone, I just traded my wife’s Vulcan S for a new KLX250. I’m so exited to start to play in the dirt. I have some basic MTB experience but I assume dirt is probably very different from what I’m used to in the tarmac.

I did some light research on SM change for this bike and it looks like my only options for this is to either do SF wheels or buy some from warp9 or others. I was wondering if there is a tire choice for the stock wheels that have “good” enough tires for some light track work. Specifically, like a go kart track? Also, the stock wheel sizes according to bikebandit is 3.00-21/21 and 4.60-18/18; what exactly does this mean? I’ve never heard of this type of size. Can other sized tires fit the KLX? So many questions and thank you in advance.

 

First, if you like mountain biking, definitely ride the bike without doing anything like an SM conversion. See how it works. I rode a KLX650 for 20 years without ever going SM, chasing my SM and sport bike riding friends around the back roads of SE Ohio, foot hills of the Appalachians. If you're in the right spot of Wyoming you don't want to SM the bike, you want to play with the dual sport aspect.

If you want to spend the money do the 17 wheels, but save the 21/18 for dual sporting. I will tell you I have about 40,000 miles experience with Duro Median HF903/904 - 40 dirt/60 road - dual sport tires riding hard on tight winding roads and can tell you they do stick well. The tread works great off road, the compound works well on pavement. Unless you're racing they will likely do fine. I have seen a NASMoto race where one rider on an old XR600R with the 21/18 stock set up running street tires (old ones in fact) out rode riders on full on SM KTMs. Amazing, but proof the tires aren't everything on pavement.

The 21/18 is the norm in sizes for off road, the larger diameter dealing with rough conditions better than smaller wheels..

The 3.00-21, 90/90-21, and 80/100-21 are the norm in front tire sizes. I'm running the 90/90 on both the 650 and 250, I would probably try the 80/100 if Duro made one, I think it would be a shade better for off road. Lots of tires available. I ran Avons until, when laid off from work, I tried the Duros, which were significantly lower priced. I never went back to the more expensive tires. High buck doesn't always dictate quality. Different terrain calls for different tread, which is likely more important than the manufacturer.

The 18" rear is common for off road, has been for decades, although some will have 17" like my 650. The English measures for tires are 4.00, 4.10, 4.50, 4.60 and so on. They don't make sense, the 4.00, 4.10, and 4.60 uesed to be near the same width, the .00, .10, and .60 indicates profile. The 4.50 is 4-1/2", I'm not sure about the 4.60 though. Metrics make so much more sense, 80, 90, 100, 110, 120, 130 are the metric widths and 100, 90, 80, 70, and 60 are the cross sectional height as a percentage of profile, an 80/100 will be 80mm wide and 80mm tall, a 100/90 will be 100mm wide and 90mm tall.

One thing to realize in tire choices - bigger is heavier and takes more power to rotate and to overcome friction on the contact patch. Supermoto bikes have fat tires, just the way they're done. Off road bikes run lighter narrower tires to maximize performance for the power at hand plus larger diameters to deal with the rough terrain. The narrower front tire can knife down through loose surfaces to get some grip on the base surface. Larger wider rear tires require more power to rotate them, due to the weight and grip. You can get too much grip when riding off road. There are times a bike needs to spin up. I was riding sand and to get rolling without thrashing the clutch, I needed to spin the tire. Mud is somewhat the same. A rider may need to spin up the engine to avoid bogging and spin the tire to clean the tread (throw the mud out).

For what it is worth. My KLX250 was running a 120/80-18. When I chose a rear tire I went with past off road experience and with what off road bikes have. The MX/off road bikes, which run knobby tires using the carcass measure instead of the tread, indicate what I'm saying. The 250 MX uses a 100/90 knobby, the 450 runs a 120/80. Tells you a lot. If that significantly more powerful 34.8 hp 250 motocrosser could run a fatter tire it would. That is what I kept in mind when picking a tire for my far less powerful 250 dual sport. Plus when racing in the 70s, I saw 125 riders running a 4.50 rear knobby on their 125s bogging and struggling, while riders running 3.75 and 4.00 having far less problems in loose or muddy conditions - fatter isn't always better. I ran a 3.75 on my Suzuki TM125. Even the 250 riders ran 4.00-4.50 instead of wider ones, like the 5.10 wide.

I went with the narrower 4.10-18, which would be about the same a a 110/80. Duro did not have the 110, only the 4.10, but their site listed the size and it was right. [Side note - use manufacturer web sites to find actual dimensional sizes.] They did have the 120/80-18, which was near identical width to the 4.50-18. A half inch doesn't seem like much, but it is when off roading. One big benefit - price. The narrower tire is significantly less than the wider one, $62 for the 4.10, $82 for the 120 in my case.

This is not to say running the 120 is bad. I just took what I saw and knew along with how I wanted the bike and tire to perform when making my choice. Others may have different reasons for their choices.

I will say there was one side benefit for me - the bike looks lighter in the rear, more like a motocrosser.

 

 

Your first time on dual sport tires will feel squirrelly, but after some time you get used to the feel and can start trusting the tires more and more. I can only speak for the Duro tires since I found them to do everything I wanted on the 650. I haven't pushed the 250 quite as much as the 650, not enough miles yet.

 

Shinko 705 tires are awesome in light dirt and corners...i run those on my street rims and got a second pair waiting when these go bad