Around about 30 miles an hour the handlebars began to shake a little. Not so much to scare me but enough to make me wonder. I was curious what could be causing this. Ive asked around and got a few different answers varying from Bad front tire to fork seals to wheel bearings. I was curious if anyone could help me with my problem. thank again.

Also curious to know if a 180 rear tire will fit on the stock 1996 CBR600f3 rear wheel.

 

A wobble at a particular speed usually indicates a wheel balance is due, but everyone else is right in saying it could be one of several things like bearings. Fork seals, well usually oil running down your front forks will tell you that that's the problem, also throw in head bearings, swing arm bearings & bent rim, just to make you more paranoid. Wheel bearings can give you the same feed back at the bars as a wheel balance, I've been told by my mechanic that the F2 & F3's are prone to front wheel bearing problems, mine have never had an issue. What sort of mileage is on your bike?
Bearings can be checked out pretty easily with a few simple tests, but the bike needs to be on a stand (center). Also check to see if the balance weight is still on the front rim, had the same "wobble" happen to me & it turned out that the balance weight had fallen off.
Not sure about the 180 & your clearances.

 

My bike just broke 18,000 on the clock last weekend. its also stretched 12". didnt know if that was information that might be needed. but it just started doing it yesterday. it was the first time its ever happen. but i was also riding me and my girlfriend. do you think that would have any effect?

 

Have you checked your tire pressures? With your GF on the back, there is weight transfer off of the front of the bike, this could definitely make things shaky, but I think probably more so when you were accelerating.
Double check your rear rim is adjusted straight, this can definitely cause a wobble.

 

I had that problem before. 50 mph there was a wobble, but it evened out at a faster speed. It was just the wheel out of balance. All good now. I have a 98, and I have a 180 on the rear no prob.

 

/\/\/\/\ Same for me, when i first got my bike it wobbled then i had it balanced and its all good now.

 

Just check the balance as other guys said. If the wobble goes away on faster speeds the tire is out of balance. The same with cars.