Well i went through the fitment guide and it seems like there is an absolute boat load of info for the FX4's but not much else.

For a 2012 SCcrew with 5 1/2 ft bed 4x4 with the rough country leveling kit will i be able to run some 35/12.5/18's? Basically the larger tires on the stock rims that come with the XLT chrome package.

Does anyone know if that will work with minimum trimming?

 

There is a thread in recently where a guy has 35s and says he doesnt rub. Seems to me it should work

 

yes they will fit

 

Even with the stock 18" XLT chrome package wheels?

 

that is a 20" with 33's and I have the 2.5 rough country level. I believe your stock 18's with a 35 will fit since stock wheels are generally a 0 offset and mine are 20mm.

 

The tires will fit your wheel wells with no rubbing but 12.5" tire is to wide for the 7.5" stock 18" wheel, you can run them but it's not recommended. I have the same wheels as you and had to go with a LT295/70R18 trail grappler from Nitto.