I am new to the board. Its looks like there is alot of good info on here. I am going to put on a 2 1/2' leveling kit on my 06 Csrew F-150 4x4 and then get some new wheels and tires. I am going with 17x9 wheel (the factory rim is 17") so as i understand i should go with a 33" tire since Im going wider then the factory 7 1/2" wheels? I will probably get the BFG 285/70/17 but would a 305/65/17 fit as well? I guess these two tires are the same height but the 305's are a bit wider. I want the tires to stick out a little but not much (maybe 1 inch) so what backspacing do I need? Thanks for the help.

 

305 65 17 will fit, the only thing is that it may not stick out at all.. it all depends on wat backspace ur wheels have.

 

I agree. Your OEM wheels are 7.5 inches wide with 5.5 inches of backspacing. So you can use that as a reference point. A commom size for aftermarket 17's is 17x9 with 5 inches of backspacing, which means the wheel will stick out 2 inches farther than the OEM wheel.

 

Tonka Truck 33 is that 305/65/17's on that truck in your pic? If it is what brand are they? I really like the BFG Mud tires so I will probably go with the 285/70/17's. The ProComp wheels I was looking at say 4.75 backspacing so I guess those would stick out at least 2" if not more. Maybe Ill have to find a wheel with less backspacing. I really dont want to use the factory 7 1/2" wheels.

 

I'd try to find a wheel with more backspacing like 5.5 or 6 inches.

 

I have a 06 FX4. At the moment, I have 35/12.50/18 Nitto Mud Grapplers on 18x10 wheels. I have a leveling kit on it, but I'm about to buy a 6 " suspension for it. I don't have much experience with this whole wheel spacing thing. How do I find out what my spacing is? I want to go with some 38/14.50/18 tires with the 6 " kit, but I need to make sure they will fit without rubbing too much. I don't see why it wouldn't fit seeing as how I'm running those 35's without rubbing.

 

This is how you measure backspacing.