Hey fellas (and gals) - I drive an '08 JK 2-dr, and really appreciate all the info here on the forums. I am, however, still sort of perplexed on several things. I'm not very mechanically inclined, so reading some of the posts is like reading Greek for me. I'd appreciate any insight that anyone can provide on the following questions:


Wheels-
I’m very confused with the entire back-spacing and wheel width subject. For instance, I’m looking at the MB Wheels 72 (16X8.5 5-127 -6MMS), and wondering if these would be sufficient with a 2.5” lift?

Tires-
Looking at the BFG KM2's (which seems to be a favorite among Jeepers), there are several sizes available. I'm not altogether sure what the numbers mean when looking at a tire.

For example:
285/75R16 – I believe that I’ve figured out that the 16 at the end is the size of the wheel being used. What is the 285/75R?
With my previous question about wheels, what size of tire would I want? There are several that have the 16 at the end, and would fit that size wheel.
How large of a tire can you fit on a rig with a 2.5” lift? 33? 35?

Lift-
I read through the FAQ, and from what I gathered, I’d need the following for a 3” lift –

1) Lift Kit
2) Adjustable Front Track Bar
3) Frame-Mounted Track bar Relocation Bracket
4) Bump Stop Extensions
5) Shocks
6) Rear Sway Bar Links
7) Rear Brake Line Extension Brackets
8) Adjustable Front Upper and Lower Control Arms
9) Adjustable Rear Upper and Lower Control Arms
10) Double Cardin U-Joint Style Drive Shaft

For a 3” lift, I found the “Full-Traction Jeep JK Wrangler 3 inch Premium Flex Suspension System” at northridge4x4.com. It appears that this has most everything in the list above. Now I’m curious if the above list also applies for a 2.5” lift? Looking around on Quadratec, I found the “TeraFlex 2.5" Lift Kit with Shocks.” Would it be more beneficial to get the kit without the shocks and look for higher quality shocks?
Lastly, if I was just to take the Jeep to a local 4x4 place and told them that I wanted a 2.5” lift; would they know to include all of relevant parts in the list above? Not knowing much about this type of thing makes me nervous.

Gear Ratio-
Since my rig is a manual transmission, I’ve found that the gear ratio is 3.73. I’m not sure if this is 100% correct though. According to several posts I’ve read, it would be beneficial to get it re-geared if I were to put different tires on the Jeep. What would be sufficient? Where do you take your Jeep to get this type of work done? The dealership? How much does something like this cost?

I apologize for the wall-o-text and once again really appreciate any help.

Thanks-
Blake

 

Welcome to the Forum!!

I'm running those same wheels. I have looked around and even asked the guys at Discount, and still can't get a straight answer on what the BS is on them. Near as I can tell, they are somewhere around 4.5, and will be fine for you. (there are a few pics in my gallery)

For the tire size, search on 'metric tire calculator' or anything similar to that through your favorite browser. There are a lot of sites out there that will let you plug in the metric numbers and then convert to something that us americans can understand. The other option is to just look at the specs list for the tires you want. Somewhere to the right they will have the mfg's stated height and width. (something to be aware of is that the listed height is not the 'actual' height. ie, if they list a tire as 35", you can pretty much bet that it will be around 33.5-34" when mounted on your jeep...)

The faq's have good info on how big of a tire you can fit at various lift heights. A lot depends on how you are set up. If you chop the flares or go to flats, you can run 35's with no lift. (with some trimming and bumpstops and steer stops and stuff) With a 2.5" lift, you can easily run 33's. You can run 35's, but they may rub when flexed, especially if you disconnect.

One thing to note when you are looking at lifts - coils generally give more lift than advertised!!! (kinda like tires are smaller than stated...) Search on the specific lift you are looking at and get some info on what lift heights you can expect!! For a 3" coil, plan on 3.5-4".

Every shop will have lifts that they will try to talk you into. These are generally the kits that they make the most money on, and are not necessarily the best kits for you! Get prices and opinions from several different shops, and be sure to compare the components.

For gearing, again there is some info in the faq's, and there is also a great rpm chart for you to plug numbers into. Start there. If you are going to a 33" tire (the 285's you listed earlier), then you won't need to worry about gears. If you go to a 35" tire, you might want to jump up to 4.88s. Expect to pay in the $1000-$1500 range for gears, parts/labor out the door.

DO NOT go to the dealership for any of this. Go to your local 4x4 shops and drivetrain shops, and talk to local 4wheelers to see who they recommend.

 

This is where I started:

https://www.jk-forum.com/forums/show...ery-Newbie-Has

Welcome and enjoy

 

Gearing... if you currently have 3:21 gears and go to 285/75-16 IMO you do need gears. The JK is a slug with them and the 4:56 gears I had installed made a lot of difference. They are a good compromise between off road and highway use....

 

285 75 16.

285 = the tires width in mm. Divide by 25.4 to get inches.

75 = is the aspect ratio. which is the hight of the sidewall as a percentage of the width.

16 = is the wheel size.

so in the example above.

The tires width is 285 / 25.4 = 11.2 inches wide ( to convert to inches from mm)

The tires height is 285 x .75 = 213.75 (because the sidewall height is 75% of the width)

213.75 x 2 (Because there are two sidewalls in the total height of the tire.) = 427.5

427.5 / 25.4 (To convert it to inches) = 16.8

16.8 + 16 (Wheel diameter) = 32.8 is the height of the tire.

Hope this helps.

P.S. You can run this size tire with on lift. I run 315 70 17's on my wifes with no rubbing.

 

Easier just to go to their website and look at the specs...


From BFG's specs for the KM2:

Tire Size - LT285/75R16/E
Max Load - 3750@80
Overall Diameter - 33.1
Rim Width Range - 7.5" - 9"
Section Width - 11.3"
etc...

 

Easier but not as much fun. Ha

 

On the lift kit side of your question you have listed a lot of things that are nice to have, but aren't necessary, at least not right away.

Look on the forum a bit closer to decide what type of kit you want. The best advice is to spend a long time researching the lifts and asking questions before you commit to anything. Decided what you budget is and what your offroading/lift goals are.

There are budget boosts, coil lifts and combinations.

The need for new drive shafts depends on your model, 2 or 4 door, auto or manual.

Also you may not need all 8 control arms, maybe none, maybe just 2, you have to decide on that priority. There are a few threads that talk about the purpose of each set of control arms.

You may want disconnects on the front sway bar.

If you are in a hurry I would still recommend that you spend a long day researching the subject on this forum. If you want some other opinions call any of the suspension vendors on this forum they usually are very helpful. I personally have called Dave at Northridge4x4 many times and found him to be very helpful.

 

If you have any questions on the 3" premium plus kit please ask or talk with Dave at Northridge4x4.


We designed the 3" Premium plus kit to include everything you need to properly lift your Jeep 3". (minus shocks) You can do it with less parts but it will not drive correctly and you will end up buying the additional parts in the end.

With the 2 door its more important to have the control arms to adjust your pinion and caster angles. The rear driveshaft is at a steep angle. If its not corrected you driveline will explode.

Even with the control arms you still will need to invest in a rear driveshaft. it wont be needed right away, but it will need replaced.