Just installed a 2.5 tereflex BB on my jk unlimited X . I am going to run 33 mud terrains. What backspacing should I get for my wheels? I was going to get a set of black rock steelies. Advice?

 

4.5 will do the trick.

 

is it a good idea to go to a 16" for a better price and tire selection? Will they fit?

 

Yes, 16's will fit.

Some 15's are iffy, some people need to grind the calipers to make them fit.

16" tires are generally cheaper than 17's (although the prices have changed some) and certainly cheaper than 18's.

Smaller diameter rims will allow more tire flex when aired down, therefor a little more bite. Larger diameter rims will offer a bit more control on the highway.

I am running the stock 17's, for me they are a good compromise between the extremes.

 

as mentioned, 4.5" would be optimal with 12.50" wide tires. factory is 6.25" and if you install a set of 1.5" wheel spacers, that would give you 4.75" which is close enough. as far as wheel diameter goes, with 33's, 15" or 16" is fine but, if you ever plan on going 35's or bigger someday, i would recommend that you stick with 17's

 

so what Im understanding is on a JK X U with 17's I should get 17 X 8 or 17 x 9 with a 4.5 " backspacing. Any reccomendations on 33's and where should I buy?

 

I had a great buying experience with Discount Tire Direct. They are a sponsor on here and their rep, Travis, was extremely helpful with all my questions.