Wheels / Tire Size / Backspace / Offset
 

Hi, my 2000 XJ has a 4 1/2" lift, 17" wheels with 2" (approx.) spacers / adapters (one tire place told me these are spacers and inherently weaker than wheels with equivalent / proper offset; another place told me I have adapters and are fine / strong to use. I don't know if they are spacers or adapters though. The tires are 255/75R17. A prior owner cut the fenders way back (further than necessary), resulting in plenty (more than plenty) of room for big wheels and big tires.

I will replace the tires soon and am considering replacing the wheels so that they are "pushed out" a little more (broadening the stance of the vehicle). My fenders are cut quite a bit so I'm not concerned about rubbing of tires on fenders.

Below should be some pics for reference.

Question1: How much (how much more?) can the wheels be "pushed out"? (I think this refers to how "little" / minimum "offset" I can run, right?). And is there a downside to pushing them out with wider than 2" adapters?

Question 2: If I keep the current wheels, what size tires can / should I run? (I do not want mud tires. Rather, I will probably get an aggressive all terrain, since I use this jeep as a daily driver and as occasional weekend warrior.).

Question 3: As far as I know my rear end (rear differential?) is stock. I've included a picture, can you tell from that how it is geared?). The jeep currently feels a little sluggish going up hills at 40-50-60 miles / hour. Do I currently need to consider re-gearing (if I stay with current tire / wheel size), or if I increase tire size at what point re-gear?

Thanks to all. This is all new to me and while I have read a lot, nothing takes the place of experience!

Here is another pic:

And a pic of the wheel adapter / spacer (?)

One more pic of tire / wheel / fender (sorry for the rotated view; I can't get the picture to orient correctly when I upload):

Wheel spacers are perfectly fine on and off the road. The only difference between wheel spacers and wheel adapters are if the axle bolt pattern is 5 on 4.5" while the wheel uses a different bolt pattern. Then they would have used an adapter instead. They both add width in the same fashion.

If I were you I wouldnt go much wider. I dont know about where you are but around here you will start getting pulled over for no fender flares.

Do you have adjustable lower control arms? Your front tires are pretty far rearward in the fender opening. You might look at pushing your axle forward slightly. Then you could run a 33 or even 35.

As far as gearing goes, if you have the money you should definitely do it. Helps from buring up clutches if in a manual or burning up bands if in an auto. Also can help fuel mileage as well as power band. Play around with this calculator here.
http://www.grimmjeeper.com/gears.html

Stock setup would be
Transmsion - AW4 if auto/AX-15 if manual
T Case - NP231 or NP242 if you have the full time option.
No underdrive
Axle gears - 3.54 if auto/3.07 if manual I believe??
Tire size - 225/75-15

Then enter in your setup on the right. Compare MPH to RPM in each gear. That will help show you where the power band should be and where it is.