Just curious why you are looking at the TKC80's on a bike like the KLX250 that literally has hundred of tire choices available for it?
The TKC's are popular with some of the big Adv bikes because that's the most knobby tire that fits, but on a KLX, you have everything from full on road to full on dirt tires and plenty in between. I'm not sure weight wise, but I would almost guess those would be a pretty "heavy" tire for such a light bike too.
For bikes like the KLX250. If you want full on knobby, I would look at the MT21 or D606. Actually a popular combination is the D606 rear with the MT21 front. I have a set of MT21's on my WR250R and they are nice on that bike.
For something less aggressive but with decent road manners and decent in the dirt is something like the Shinko 244. You can get a set under $100 and they do pretty well in everything but the deepest mud.
I'm currently running a set of the Shinko 700's on my DR650. They are just a little bit less aggressive than the 244's but have much better road manners and that's where they really shine. But if you need to go offroad, they still work fairly well.
There's plenty more tires out there I haven't even touched on.