I have a 07 lariat 4x4 screw with the factory 20's. I'm puttin a 2.5" front level and 3" blocks in rear. I have seen some people on here that have the same set up but their truck is a FX4 running 35 x 12.5 on the 20's with little rubbing and minor trimming. What I was wanting to know is if there is any difference in the front ends of the lariat and FX4's that wouldn't allow me to run the same tires.

I was also wondering what the is difference in the specs. on the factory 18's and 20's? Because I have seen where some people say you can't fit 35's on the 20's but you can on 18's.

 

There is no difference between the two. The FX4 have rancho shocks, but they do not change anything.
As far as rims go, the 20's are a little wider (8.5 vs 7.5) I do not know about that OS and BS. Anyways you can run 35's on them too, but more than likely you will have rubbing at full lock.

 

I believe the OEM 20's are 8.5 inches wide with 6.5 inches of BS vs. 7.5 inches and 5.5 inches of BS on the 17's and 18's. The increased BS on the 20's can cause some 12.50 inch wide tires to touch the upper control arm/ball joint.

 

Check my album for exactly what you're looking for. My tires are 325/60/20 with are a tad larger than 35x12.50. I needed 1/4" spacers to get them off the upper balljoint and some minor trimming was needed on the inner plastic. It still rubs at full lock. It rides well though and the spacers didn't cause any problems with vibration or balancing etc.

 

Are some spacers better than others? And why do some people say not to use spacers? And to you put them on the back to make it all equal?

 

There seems to be a pretty common issue with vibration using spacers, particularly on the 04-08 models. I didn't have a problem, maybe I was just lucky, maybe it's more of an problem with larger spacers. Mine are cheap ones, my tire shop threw them on for free but I think they were only around $10 a piece to buy. I was prepared to buy some better ones, but it doesn't seem to appear they I need to. I put them on front and rear, I needed a tiny bit of clearance for the parking brake cable back there.

I did find a company that custom makes high quality spacers, fit for your axle/hub/rim interface. http://www.motorsport-tech.com/