I was thinking about putting a 3" body lift on a 91 isuzu trooper, I was wondering what I could fit without rubbing.. my guess was maybe 32" but now im thinking 31's would be a better bet so if you know, help me out
If you do a 3" body lift, 33s fit easily. Some have run 35s with a body lift and some light hammer work.
You can also fit 33x10.50 without a body lift. I ran them on 15x7 neutral offset wheels and had no body rubbing.
Keep in mind that a suspension lift won't allow you to run larger tires, it just increases ground clearance. If you do a suspension lift and extend the bumpstops (thus limiting suspension travel) you will be able to fit a slightly larger tire, like a 32x11.50.
I was under the impression that a 3" susp. lift would clear 33s, but, if 35s are the tread of choice, the 3 + 3 must be performed. How does lifting the entire chassis (frame and all) not allow for a larger tire? I've been reading these boards for a few years now, and this goes against what I thought I understood. Confused... :?
Well, just lifting the suspension doesn't change how far up into the wheel wells the tires will travel.
The front suspension is the important one, ignore the rear for now.
Let's assume that the range of motion of one front tire goes from 0" (where the suspension is completely compressed and the lower a-arm is touching the bump stop) to say 10" (at which point the upper a-arm is touching the droop snubber). The 10" of wheel travel is just an estimate, but it doesn't matter how much travel you have for this example.
Lets now assume that from the factory the torsion bar was set so that the whole system sits at 3.5" from the top. You have 3.5" of travel upwards and 6.5" of downwards travel available. When you "crank up" the torsion bar you change the static ride height. So, a 4" lift change the static position to the 7.5" point. This means that you now have 7.5" of upwards travel available, and 2.5" of downward travel. You haven't change where the tire is capable of going.
If you fit larger tires, they can still travel through the same range of motion that the smaller tires would, no matter how much lift you add. It may be harder to get the tire to move all the way up, but if we assume that you are adding larger tires with the intent of going off-road, those off-road conditions will put more force on the tire pushing it up, which will move the tire all the way up to the example 0" point.
The only way to change that range of motion is to limit it. You limit it by extending the bump stops down. This can make the uppermost point 1" or 2" from the top.
You can see that there isn't much room at all for a larger tire. The next step for fitting a larger tire is to move the sheet metal out of the way, and that's what a body lift does.
So if you are doing a suspension lift and not changing the bump stops, you aren't changing what size tire you can safely run (meaning without contacting the sheet metal). The suspension lift then just gives you more ground clearance. A body lift does nothing for ground clearance (by itself) but it does allow you to run larger tires (typically 33x12.50 on a 1st gen Trooper) which iwll give you the increased ground clearange.
Both types will raise the center of gravity and negatively effect the stability of the truck, so whatever you do, be careful and learn the way the vehicle handles post-lift.