My front tires start to vibrate when I reach 30mph

Tires, move the rear tires forward and see if the noise moves, if it changes replace the tires.

There are many stages of vibration. The most common is in the steering and USUALLY a steering dampner will correct this. However, your description is not real defined and until the technician actually experiences it, it cannot be properly diagnosed

This is built into the car and is a nation wide complaint on all Jeeps. Contact the dealer for help or the factory assistance line. You could try adding more negative Castor adjustment to the front end , that may help.

If the vibration started after you had the tires replaced, I'm gong to say its a tire problem.
Spin balancing machines turn the tire and wheel at about 30mph and the high spot is marked for weights. If the tire is not made well, a vibration at a higher speed may not show up on the machine.
I would take the car back and have the tires re-balanced again at no cost.
Take the service manager for a ride before the job is redone to verify the vibration.

It sounds like a bad tire, possibly a broken belt. Check the sidewalls and tread of all the tires for bulges. If good it probably is a bad wheel bearing. Try to isolate from where and what side. If the noise gets louder turning one direction but not the other, then more likely a bearing. If it stays constant both directions but gets louder with speed, then suspect a tire.

Have you checked the wheel balance on the front wheels?

FIRST THING THAT IS COMMON TO A BAD TIRE...SWAP FRONT AND BACK TIRES AND SEE IF THE PROBLEM GOES AWAY

Generally, the tire vibration only arrives at 60ish.
However, if you have a distorted tire, or worse, more than one, or even worse, Buckled Wheels!
You are inevitably going to experience vibrations, at varying speeds.
Take the wheels off, and make sure, the wheels are actually still,, er, circular.
It's best to put them on a Balancing Machine, then you can see how bad they are.
If the problem isn't solved soon, you may well be finding yourself, forking out for new wheel bearings.
That should do it.
Happy motoring.
Oh, & Don't forget to rate:))

Tires would be the 1st place to check. If you seem to feel it more in your legs then it is likely the front, if felt more in seat bottom then could be a rear tire. Depending on how severe the vibration is there could be a tire developing a tread seperation and should be checked right away. A simple balance of the tire and wheel assemblies may be all that required also but when on a balancer they should be able to tell if the tire has a more severe problem.
Driveline components could cause vibrations also however if the above sounds like it fits then check that 1st.

try gitting the wheels ballanced and see if that helps and have the front end check out. have the wheel barings tie rods and ball joints checked