Q-Link XF-200 Tires

I have an XF-200 (the Qlink that is designed for street rding), but I put off-road tires on it because I live in the mountains and use it as a duel sport. Nevertheless, I have noticed that the off-road tires on my bike are still the same size as the street bike tires (the front tire is significantly smaller in diameter than the duel sport bikes).

Can anyone explain why the front tire is so small and if it would be in my best interest to put on an off-road size tire instead (I also just popped the front tire so I think I either need to patch it, gorilla snot it, and keep riding or simply replace the entire tire).

So here are my issues with less rambling:

1) What is the theory behind a smaller front tire on street riding and a larger front tire for off-road riding?

2) Can I use the traditional size duel-sport tires on my XF-200 or should I stick with tires closer to stock size?

3) Replace the front tire or patch/gorilla snot?

I'm not the word by any means but I might be able to help answer a few questions.

1. A smaller front tire is better for street due to the nature of driving on tarmac. You're mostly just driving straight. and i's more conducive to that. A Larger front tire can more easily roll over objects and obstacles, is more agile and responsive but subsequently isn't as good for driving in straight lines on tarmac and stuff.

2. You should be able to use most 17" tires but ideally and traditionally I think most dualsport more off road oriented riders have a 21" front thin diameter wheel, with a wide 18" wide diamter(for traction) rear wheel. You'd be fine with keeping our 17" wheels with offroad tires, but if you aren't happy you can think about replacing just the front with a 21" wheel and tire.

3. If it was me, I'd replace the tire if it was within my budget. I don't like to take chances.

If I am wrong, please by all means correct me