Have a 08 fx4 with a 2.5 inch leveling kit and want 18 rims. Does anyone know the biggest tire I can put on that won't rub?

 

Sure do. So does the sticky at the top of the forum. Let me know if you need the link.

 

go to www.tirerack.com and thatll tell ya

 

Are you using your stock 18" wheels?

With the leveling kit and your stock wheels, you can put on 35"x12.5" tires. Remember that they can't have a section width of more than 12.5" or they will rub.

 

No I got some kmc xd monsters 18 inch

 

Use the search function and you'll easily find the answer to your question sir. This topic has been talked about thousands of times and as scobar has stated there is even a "sticky" thread about it at near the top of the thread list. Not being mean or arrogant towards you just informative and helpful for your future questions. Have fun on here its an amazing forum with great information and knowledgeable members.