You see them all the time:   Light trucks, Sport Utility Vehicles, Jeeps, and more, coasting down the  highway, sitting atop towering truck suspension lift kits and sporting a set of  tires so big that a person could live in them.   If you're the curious type looking to lift up your own rig, a more  important question than "How do I get my ride to do that" is "Why should my  ride do that?"
There are several reasons why people might customize their  vehicles with suspension lift kits, as well as quite a bit to know before you  get started.  If you're a seasoned  veteran who has conquered the most vicious terrains and knows your vehicle  better than your own mother, there probably isn't much for you to learn here.  On the other hand, if you're just getting  started and want to familiarize yourself with the basics, read on.
Why should I lift my  ride?
Glad you asked.  Equipping  vehicles with a suspension lift kits involves much more than buying the sexiest  looking truck lift kit and then dropping your ride off at the local  mechanic.  Actually, chances are good  that if that's all you plan to do, lifting your ride might not be right for you  in the first place.  Installing truck  suspension lift kits requires some hard work, a bit of technical savvy and  consistent upkeep and attention to your vehicle's components.
The first determination you need to make when considering  suspension lift kits is what you want to do with it.  There are essentially two main purposes for  installing truck lift kits:  style or  function.  Although the two are somewhat  interrelated, it's still important to consider which purpose you most wish to  pursue, as it will assist you in making the correct modifications to your  vehicle.
Style:
Let's face it:   Transforming a vehicle into a style statement has been a popular hobby  ever since the advent of tailfins and flame decals.  As much as we all might chuckle at a hybrid  hatchback sitting on 18" wheels, or the family sedan with a wing that resembles  the Seattle Space Needle more than a spoiler, we also find our own vehicles  having fuzzy dice hanging from the mirror, or a bobbling hula dancer statuette  on the dash.  As far as style is  concerned, adding truck lift kits makes more of an impression than anything  else you can do to your ride.  Heads turn  instantly at the sight of a lifted rig with massive tires that appear to be  sprouting fangs and an exhaust system that scares stray puppies into hiding.
When it comes to adding suspension lift kits to make a style  statement, looking good is the easy part.   Sometimes it's easy to overlook general, everyday performance in the  midst of decking out a ride.  For this  reason, choosing the right suspension lift kit with attention to comfort,  reliability, durability, safety, and not to mention price, should be given just  as much consideration as those precious inches you want to add.
Performance:
So you've made the jump into tuning your rig for the  off-road world, and you're ready to take the plunge to invest in one of many  truck lift kits.  But before diving  headfirst into a custom truck lift kit and gigantic tires, there are a number  of issues to address to ensure a correct setup.   The first step is to ask yourself what you will be doing the most,  whether it's slow-speed rock crawling, high-speed desert racing, general  purpose 4 wheeling, mud racing, or long distance open country treks.  From there, you can narrow down what you need  to do in order to customize your vehicle to suit your needs.
Whether you're just starting out, or you're the experienced  professional, tuning your rig for optimum off-road performance is an expansive  hobby with numerous factors to be wary of.   The possibilities are limitless, which can sometimes make it hard to  determine exactly which suspension lift kits are ideal for what you want.
Where do I begin?
As if determining which suspension lift kits to purchase  weren't complicated enough, installing truck lift kits can alter other  components in your vehicle, sometimes causing unforeseen issues that could  affect performance or be potentially detrimental to the vehicle itself.  For example, drive shaft length, steering  geometry, brake lines, highway performance and handling, gear ratios, and  overall weight are just a few of the factors that could potentially be impacted  by adding truck suspension lift kits.
Finding ample resources to determine what products you need  can be difficult.  Speaking with a  mechanic can provide some insight.  Reading  factory service manuals, off-road magazines, internet message boards,  manufacturer's guides, and a number of other resources can help as well.  But by far the most useful way to determine  what truck lift kits are right for you and your vehicle is to consult an  experienced and knowledgeable person who has a vehicle similar to yours and  uses it in the manner similar to what you want to do.  Not only can such a person suggest the  correct products, but also likely has experience with installation tips and  general drivability.
In the meantime, here are some of the basic elements of  suspension lift kits for you to keep in mind as you plan your modifications.
What does a  Suspension Lift Kit do?
Clearance
For starters, one of the foremost reasons for installing truck suspension       lift kits is to raise the height of your ride off the ground to enable       steeper ascent or descent off-road, and higher ground clearance.  In general, it makes sense that when       driving over boulders, slogging through mud, coasting across the desert,       or even just making your way through the occasional forest trail, higher       clearance facilitates negotiating certain obstacles.  This can often be a tricky bit of       artistry to manage, as higher clearance also raises your vehicle's center       of gravity, which can reduce handling.
Larger Tire Fitment
The general consensus suggests that larger tires equate to more traction,       right?  Well, not entirely.  While larger tires may provide some       improvement to traction in off-road conditions, there are other ways to       improve a vehicle's traction that are far more efficient than simply       bulking up the rubber.  Aside from       the obvious stylistic discretion, the main reasons for adding larger tires       are for higher vehicle clearance for improved performance in mud, deep       snow, rocks, and deeply rutted trails.        Certain tires designed specifically for off-road conditions can       improve traction depending on the circumstances, but the added clearance       is the most immediate and direct benefit of larger tires.
Factors to Consider  with Truck Suspension Lift Kits:
Installation:  Many manufacturers offer manuals for  installing truck lift kits onto certain vehicles; however, some installations  are quite intricate, requiring some welding or cutting in order to add some  necessary components.  In this case,  having a trusted mechanic or a few knowledgeable friends is the best  resolution.
  Additional  Modifications:  Upgrading to truck  lift kits with taller tires also means that a number of components may require  part upgrades or some tuning to compensate.   For instance, a truck's engine is tuned at specific gear ratios to  propel the vehicle.  When adding taller  tires, the gear ratios must be tweaked accordingly, since the engine has to  spin much larger, heavier tires.  Again,  consult with more experienced individuals for further insight.
  Highway  Performance:  Larger, wider tires can  sometimes result in instability on roads or a noisy, uncomfortable ride,  particularly at high speeds.  Also, more  aggressive off-road tires tend to wear faster on the highway, and traction  might not be as great as you would expect on wet roads.  In this sense, larger tires can sometimes be  a gamble without any direction from an experienced off-road veteran.
  Weight:  larger tires are heavier, which can put a lot  of strain on your suspension, particularly if it's a stock suspension.  Trusted, durable suspension components and lighter  aluminum wheels can sometimes help to reduce the strain.
  Handling:  Adding truck suspension lift kits will  undoubtedly raise the vehicle's center of gravity, resulting in less stable  turns.  This is a common issue when  installing truck lift kits, but is mostly just a matter of becoming accustomed  to a vehicle's change in performance.
  Legality:  Some suspension lift kits are such a  serious change in your suspension system that it may not be legal.  Check the suspension regulations within your  country, state, or province to be sure.
  A Few Useful  Accessories:  Before installing a  lift kit, it's a good idea to first examine if any components will be affected  by your vehicle's new height.  Here are a  few useful accessories that may need to be upgraded:
  Brake  Upgrades:  Stock brakes can't always  accommodate larger tires, or will wear easily due to the added strain.
    Drivetrain and Differential:  Axles, gears, differential covers, lockers and more  ensure that your drivetrain is up to par with your suspension.
    Replacement  Parts:  Longer Control Arms and Track Bars to  compensate for the additional height of your rig.
    Shocks:  For those taller lifts,  longer shocks will ensure the smoothest performance both on and off road.
    Other Parts:   Steering linkage, slip yoke, drive shaft length, u-joint angle, and  brake lines are all worthy of consideration before installing suspension lift  kits.
  
Installing Suspension  Lift Kits:
When it comes time to install a lift kit, there are two ways  possible ways to go about it:  install it  yourself, or have a professional do the job.   Naturally, each has its advantages and disadvantages, and when it comes  to your rig, attention to detail is crucial.   A general rule to follow is that even if you know you want a large lift,  it's best to start with a small lift and work your way up.  This allows you to work out any kinks and  hindrances along the way to make sure your kit works right.
Do-It-Yourself
Even if you're not technically inclined, taking the time to learn the       inner mechanics of your vehicle is a valuable experience that can save you       time and money.   An intimate knowledge of your rig can       also allow you to make your own modifications to your vehicle if the need       arises.  There are numerous       resources available that can usually guide you through the majority of the       process; however, one must keep in mind that it's a lot to take in, and tweaking       the intricate components of your vehicle is no small matter.  It's always a good idea to have a second       set of hands or an experienced individual assisting you.
On the downside, even with the increasing availability of bolt-on kits,       installing suspension lift kits is no easy task, particularly if you're a       beginner.  Additionally, certain       instructions or resources can sometimes be misleading or based upon the       personal preferences of individual gearheads.  Often times, after installing a lift kit       you'll find yourself spending hours tweaking the other components of your       vehicle to get them back to spec.        That's a whole lot to take on, particularly if you're       inexperienced.
Mechanic
A licensed professional installing your lift kit is typically the best way       to ensure that suspension lift kits are installed correctly, so long as       you're willing to pay the labor charges.        A professional can perfectly tune your vehicle to your liking and       see to it that all components are working as they should, all within a fraction       of the time it would take even the most experienced gearheads to install       it themselves.
On the other hand, as is the case with regard to any mechanic, it might be       difficult to find one you can trust to install the kit properly while not       overcharging you for any unnecessary parts.  Also, if you're not a gearhead, anytime       there's a functional deficiency or your vehicle needs minor tweaking, you       have no choice but to return to the mechanic for service.
Suspension Lift  Sizes:
Small:  A small lift consists of 1.5 or fewer  inches, and will grant you a little more clearance and room to run slightly  larger tires.  The most common way to  gain a small lift is by using coil spacers in front and long shackles in the  rear.
Advantages/Disadvantages:  Small lifts are inexpensive and easy to       install with very few complications.
Medium:  A medium lift is roughly 2" of lift, and  is a good choice for those looking for the best tire clearance, but aren't  planning on doing any off-roading.   Common medium-sized lifts use spacer and add-a-leaf lifts, and sometimes  come with new shocks.
Advantages/Disadvantages:  You'll notice changes in handling and       performance: some good, some bad.        You'll also need strong rear springs, and if you plan to use an       add-a-leaf kit, later modification for more lift may be difficult, since       add-a-leafs are designed to lift stock springs.
Large:  The largest lifts consist of 3 to 4" or more  for an aggressive look and the best off-road performance.  A common large lift setup consists of new  front coils and add-a-leafs in the rear, plus some combination of new front  coils and new rear springs.  These kits  often include a matching set of shocks.
Advantages/Disadvantages:  Large lifts are obviously the most       expensive, and more complications are expected than with smaller       lifts.  On-road performance will       also be affected, sometimes dramatically.        But a large lift will transform your rig into an intimidating       off-road machine that will stand out among a crowd.
Types of Suspension  Lift Kits:
Spring Over Axle  (SPOA):
SPOA suspension lift kits are most popular among serious  rock crawlers looking for the utmost articulation (up and down wheel  travel).  These truck lift kits keep the  tires on the ground for maximum traction, while correctly lifted springs lifts  everything out of harm's way, including the springs.
Shackle Reverse (S/R)  Suspension Lift Kits:
S/R truck lift kits are designed to provide a smooth ride  upon mild terrain such as forest roads, desert driving, and scenic trails;  however, high-speed driving on highways is not recommended.
Coil Suspension Lift  Kits:
The choice of many of the world's best-riding 4 wheel drive  vehicles, Coil Suspension Lift Kits offer unrivaled ride quality and cheaper  springs, but installation sometimes requires some welding.  The end result, however, is a suspension lift  kit that provides excellent articulation on the trail, and a comfortable ride  you have to feel to believe.
Lifted Spring  Suspension Lift Kits:
The most commonly used type of truck lift kits in the world,  Lifted Spring systems are easier to install, and an excellent choice for  first-time lifters in the off-road world.   These truck lift kits allow you to run larger tires for additional  clearance, while producing control on the highway.
Shackle Suspension Lift  Kits:
As probably the most affordable way to add inches to your  rig, Shackle Suspension Lift Kits are primarily for the truck enthusiast  looking to add larger tires, yet are not intending to do much hardcore  off-roading.  Moderation is recommended  with these truck lift kits, as Shackle systems are known to affect steering and  sway control.