question about best kind of dirt bike tire to use

Hi. I'm looking for advice about whether I should use a different kind of tire on my motorcycle. I ride a Honda XL250 (Degree) dirt bike, and use the Vee Rubber VRM 206 tire. It's a pretty knobby tire that's supposed to be good on both paved roads and dirt roads. I do 99% of my riding on paved roads (tarmac), and am thinking that I'd get better traction if I used a less-knobby tire that has more rubber on the road. Maybe something like the Metzeler Enduro 1, which is primarily for on-road riding, but advertises that it gives "satisfying performance on light off-road terrains". I've had one potentially serious fall when I braked on a rain-slick road at about 50 mph and the bike went down almost immediately (it had only rained for about 5 minutes after not having rained for a long time, so the road was especially slick). I live in Thailand, and if I decide to switch tires, it'll take some searching; the shop that sold me the motorcycle only has the knobby tires. But I'm willing to do that if it'll make my riding safer. I've also thought about having two sets of tires and switching to the off-road set if I'm going to be riding on dirt a lot.
If anyone has any helpful suggestions, I'd appreciate it a lot.
- Paul

Thanks to everyone for their replies. I'm still looking at different options. The Pirelli MT60 looks good for both on and off road. A Vee Rubber rep I talked to recommeds the Vee VRM193.
- Paul