Does the 120 front tire cause handling problems?

 

I also have a 2009 KLX SF and I put a 150 on the rear and I have had zero problems. The table below presents the OEM tire and rim information that come standard on the SF.



As you can see for the Rear tire the top width of the OEM tire is 130 mm is 5.12". I measured the rear tire rim width to be approximately 4.5". Although not shown in the table I also measured the width between the rear arms (terminolgy?) that hold the tire to be a little over 6". This number will vary depending upon where you measure, so the height of the tire can be a factor. To calculate the height in mm just multiply the 130 mm x (70/100) = 91 mm = 3.58".

If you look at one of the links stickied at the top of the first page (Off Road Wheels for KLX250SF) you will see that I put a lot of other potentially useful information regarding motorcycle tires.
https://www.kawasakiforums.com/forum...ad.php?t=29713

In summation I determined that you could put a 150 mm (5.9") top width rear tire on the SF and in fact I did just that.

Which tires do you want to put on your bike?

 

I also put a 120/70x17 on the front of mine, a 50/50 knobby Kenda 270. At first I didn't like the way the knobbies and especially the front tire handled in comparison to the OEM tires on pavement. As far as the front tire, my bike would probably handle better if I would probably need to raise the forks in the triple clamps by 5 or 10 mm (Thanks Radius). However there is nearly no where to ride off road in my area except for gravel county roads and I will eventually put the street tires back on in Spring.

I assume you're considering street tires but increasing the front tire width will probably affect your steering and handling somewhat.

 

So you put a 150 knobby tire on the rear?