Generally you want a Jack that has to use less than 50% of its rated
capacity to jack with. There is about 4000 lb of weight on your front
axle and when you jack it out inboard of the wheel you are actually
lifting more than half the weight on the axle and a 2 ton jack will
work pretty hard on such a load as will be seen by the effort required
to use it. I suggest a 3 ton bottle jack here minimum as it will
reduce effort to raise it and it will have a bigger base and more
saftey reserve capacity. The lowest capacity jack I have here is a 2
3/4 ton floor jack and I have a 3  and 5 ton bottle jack too. The 5
ton is about 20 years old now too and never break a sweat with any 4x4
or trailer axle I jack up with it.  
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TheSnoMan.com

I have a quad cab 1500 Ram.  The registration says it's 7000 lbs.  I have a
2 ton jack.  I jacked the truck up at the front right wheel, which was flat.
It took all of my strength to pump up the last few pumps.  I was afraid it
would fail, and it was creaking a lot.  Will a 2 ton jack hold safely this
load?  Theoretically, it should hold at least 1/2 the truck's weight.  But,
as hard as the last 4 or 5 pumps were, I was concerned the jack would fail.
Any opinions?

thanks
Brian