Tire sizes
 

What is the biggest size tire I can put on stock jk rim is a 325/65/18 to big

That is a common question that will require more details. what lift, gear ratio, type of wheeling you want to accomplish, axle size, daily driver etc...

You can run what ever size you want but some consequences will come with your decision.

I think the stock 17" rims are 7.5" wide. There is no issue putting that size tire on the stock rims...but as said above there may be other issues in fitting them on the Jeep but I'm not familiar with the setup on a JK.

i have a 07 and ran 285 75 16 on the stock rims with out a lift. it worked. but it works much better with a lift and aftermarket rims.

I have a 2" lift on it and everything else is stock it's a daily drive for now