When it comes to jets there a few different reasons for needing different sizes.
1: Altitude
2: How restrictive is your bike, meaning, have you changed the air filter and exhaust out or just the air filter.
3: Temperature.
As a base example, I live at an altitude of 450 feet in North west Alabama so the temp is warm and muggy most of the year. I changed out my air filter and drilled my exhaust and I have always used a #115. I just received my new exhaust today and after install I am guessing I can get by with a #125 or larger.
You can generally tell if the bike is running to rich by opening up the throttle, if the bike smothers itself at full throttle then you are too rich, if you are too lean the engine will run hot.
Another to tell is by running the bike for a while then pulling the spark plug and looking at it, you want to pull the spark plug before you do this first so you have a point of reference.
A black/brown plug means the bike is running too rich while a white plug means the bike is running to lean. It is better to run a little rich than a little to lean as a rule. The leaner the engine the warmer it will run and that can burn the engine up.
Also about the tires, You can see in the gallery of Lifan-moto my latest bike with wider tires installed.
I am running a,
100/80-18 on the front and a 140/70-18 on the rear. Your tire choice is fine but you can go wider on the stock rim in the future if you decide to
, also be careful to make sure these tires are warm after a short ride, some tires on eBay are just not sticky enough for my taste. Of course for regular riding they will be perfectly fine, but don't dive into a corner doing 50mph down a 10% grade with you knee touching the ground until you have some nice good sticky tires on your bike
Hope this helps,
Almon