Yo cyclonespoiler69,
Welcome!
Attached is a Tire Size/Lift Guide.
Some tips;
There are three different body styles in the 80-96 era. 80-86, 87-91, 92-96. In 1980 FoMoCo introduced a four wheel drive version of their Twin-Traction Beam suspension. This suspension and axle design is normally only recommended for tires up to 35 inches if off-roading is done. Tires up to 38 inches have been run on TTB but it is not recommended for heavy off-roading. The first two years, 80 and 81, the frame was sort of expiramental and is less desirable for off road use. From 80-86 the bodies and fenders were more squared off and the fender openings are generally referred to as being larger than later models. From 87-91 the bodies and fenders were much more rounded, but the grill and frontend was still partially squared off. These models do not have as large of a fender opening. From 92-96 ford made their last broncos, and these included a front end update for a more curvy look. The fender openings stayed the same from the 87-91 model years.
What follows is what size tire you can fit both stock and with the lift amounts listed.
Generally 33 inch tires will fit without rubbing issues except on the radius arms. Some rubbing may occur on the fenders under extreme flex but can be fixed with very minor trimming and if the rubbing occurs on the bumper it can be spaced out to fix this problem. A 4 inch lift can fit 35s with minor trimming but 33s are recommended to alleviate any rubbing issues. A 6 inch lift can fit up to 35 inch tires with minor rubbing if any. Skyjacker makes an 8 inch lift that can be used to fit up to 38 inch tires, but this puts a lot of strain on the TTB axle setup.
Another thing to keep in mind when doing a suspension lift is steering. If the stock geometry were to be kept in place, the increased angles would create excessive bumpsteer. To correct this, the steering geometry must be changed. The most common ways to change it are to use a drop pitman arm (either included in most kits or an option), to flip the tie rods to the top of the steering knuckles, to use Superlift's Superrunner steering system, or to use some combination.
Flipping the tie rods to the top of the knuckles works perfect for a 4" lift with the stock pitman arm. For a 6" lift, a drop pitman arm is also needed. In either case, a drop pitman arm will suffice by itself.
There is also another option to lift the rear of the Bronco: a shackle flip. Using either the front hangers for the rear leafs off a F-250/350 (there is some debate as to whether or not F-150 hangers are the same) and to install them in place of the factory rear hangers on the Bronco. This can net anywhere from 3-5.5" inches of lift. The actual amount of lift will vary from application to application and the different methods used. Sky Manufacturing also makes a shackle flip kit that utilizes a new rear hanger for the rear leaf. It accomplishes the same goals as the F-250/350 method.
Some companies' brackets are much beefier than others. Superlift, BDS, Tuff Country, Trailmaster, and Rough Country use a drivers' side brackets that bolts on in addition to the existing factory one.
Something that will vary from vehicle to vehicle is whether or not you will need camber adjusment sleeves and extended brake lines after the lift.
The TTB is a difficult suspension to align, lifting it doesn't make it easier. After lifting, you should take it to a competent alignment shop and have them work on it. If your camber is off too much, you will need adjustment sleeves, which can be pricey. Whether or not you will need these is strictly based on each individual rig. One may need it and another with the exact same kit may not. It is pretty much luck of the draw, but chances are you will need them if you want your Bronco to align properly, especially down the road.
**** Don't get cheap with the brake lines: buy extended ones as it is a very cheap price to pay considering what they are in control of. *****
When bigger tires are added, you will suffer an engine loss because more mass and a larger diameter tire is having to be moved. Changing the ring and pinion gears in your axles are one way to get this power back.
"Larger Tire and R&P Gear Info;
Your tire size may be listed as 33/35/37, etc. but the actual measuremnet of the tire could differ once it is mounted on your rim.
Also this write is assuming you have an E4OD, or similar auto tranni.
These are figures that I came up with, to do your own just do:
Circumference of tire divided by the gear ratio you want.
Then compare you answer to the stock forward measurement of 25.5"s and then you will know if it fall over or under.
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"Stock 29" tire (235/75R15), with 3.55 gears, 90.7" is circumference of tire, thus for every turn of the drive shaft, you go forward 25.5" or so.
33" tire, 3.55 gears = 103.7" circ, forward 29.2", about 15% more than stock
33" tire, 4.10 gears = forward 25.3" basically same as stock
33" tire, 4.56 gears = forward 22.7", about 11% less than stock
35"s with 4.10s = 26.8, 5% over stock roughly.
35" tire, 4.56 gears, 110.0" circ, forward 24.1", about 5% less
37" tire, 4.56 gears, 116.2" circ, forward 25.5", identical to stock (within error)
37" tire, 4.88 gears, forward 23.8", about 9% less than stock.
38.5" tire, 4.56 gears, 121.0" circ, forward 26.5", about 4% more than stock
38.5" tire, 4.88 gears, 121.0" circ, forward 24.8", about 3% less than stock.
FYI, for those who are thinking they can run a 35" tire with 3.55 gears...
35" tire, 3.55 gears, 110.0" circ, forward 31", about 22% more than stock. That means that your motor is working (and your clutch or torque converter) quite a bit harder to move your truck. That's why it dogs so bad.
If it falls "under" your motor does not have to work as hard to turn the tires, but it does it at a higher RPM. This means that as you go more "under" you lose top end. If it's "over" you'll have a higher top end, but less grunt."
By GL. By Wes.
....
Rough Country® 6 inch Installation pics in a 93
Source: by Doba (SOLD) at
https://web.archive.org/web/20100106005236/http://public.fotki.com/DOBANIN/other/bronco_build/modifications/6-rough-country-lift
Rough Country® 6 inch Installation pics in a 96
Source: by Tool38 (Bronc) at
http://www.supermotors.net/registry/12259/33712
Gear Ratio Change From Tire Change; ".by New Tire Diameter: Old Tire Diameter: Current Gear Ratio; This calculator will take your gear ratio and tire sizes and tell you what the effective or Actual Ratio is. It will then suggest a New Ratio along with a Hi and Low alternative. This New Ratio will return the vehicle to it's original performance after the addition of larger tires. Obviously, you will have to round the new ratio to the closest available ratio..."
http://www.blueovaltrucks.com/tech/Gear_Tire_RatioChange.html
