Offroad Trailblazers and Envoys

The OFFICIAL "Welcome to" thread!

New members: please introduce yourself here.

by Trail X » Thu Mar 29, 2012 1:42 pm

First of all, welcome to the forum, and thank you for joining!

Please read through this post before entering into the forum and posting. No, seriously. Read this. You will probably find the answers to 90% of your questions just by reading this post.

This post will not only introduce you to our forum culture, but also start to build your knowledge about offroading and the nature/nuances of doing so in the Trailblazer and Envoy packages. We spent a lot of time compiling this stuff.

So grab a drink, sit back, and begin your reading right here. I know its long, but stick with it. I don't think you will regret it.

What to expect on (ORTB): is a community-driven resource whose goal is to unite the population of TrailBlazer, Envoy, and other GMT360/370 owners that have a shared passion of seeking out the unpaved areas in the world. Our community was founded by and run by a small group of like-minded individuals eager to continue expanding and sharing our off-road adventures.

Our community is based on the ability to search out your answers. After you search around the site (READ READ READ like you're doing now), and still have questions - feel free to ask them. Do not expect handouts, but we will gladly assist you when you get stuck. This mantra is there because when you get stuck in the middle of nowhere with no cell service, it will be up to YOU to get yourself out. We therefore expect that kind of self sufficiency on this board.

Please read this link for our site rules:


We generally expect our users to post using coherent sentences, and to not use texting language. Please put effort into your posts, and re-read them before posting to ensure you're getting your point across. We have adopted this rule because we generally deal with technical issues, and proper communication of the issues and solutions is key to a successful thread.

Additional details regarding how to post:

Site Layout:

There are two separate sides of the site. One side is what we call the "www" side. This is the portion of the site that has a web address starting with www. This includes our tech docs, how-tos, recovery articles, news posts, and media sections (and is a very good resource!). The other side of the site is the forum. Any page who's web address begins with 'forums' is part of the forum. The forum is the user community, and hosts a wealth of information posted by our users. You will find links to both sides of the site from the top menu bar, below the ORTB logo.

Where do you start?

To make your Trailblazer or Envoy more off-road worthy, you made the first correct step by joining here at ORTB. Your next step is to introduce yourself in the Introductions (viewforum.php?f=8) section. If you have a special mission for your vehicle, state it there. Your first steps will otherwise be to search and read.

How to Search:

There are technically two separate site search methods. The first is via the 'Google Custom Search' at the top right of every page. This searches both the www and forum sides of the site and combines the results. The second option is the 'search' link from the top menu bar. This will give you detailed options for searching only the forum side of the site.

Basics of Lifting your Truck:

Lift, in the strictest sense, can come from any combination of the following 3 components:

  • Tire Diameter
  • Suspension Changes (a lift block or spring)
  • Body Blocks


In the course of off-roading your vehicle you will want to upgrade from standard street tires to off-road tires. When you make the change, you may also want to consider getting a tire with a larger diameter. The increase in tire radius directly increases your vehicle's underbody ground clearance. This is the purest form of vehicle lift because it increases the ground clearance under every component of the vehicle.

Types of tires:

There are many forms of tires. Tread patterns can range from the crazy to the mild. In general though, as off-roaders, we will choose between two types of tires. Mud-terrains (M/Ts), and all-terrains (A/Ts). Mud terrains are generally more aggressive treads with greater tread voids. This is designed especially to allow mud to be shed easier. M/Ts will be a little noiser on the road, and can wear faster due to softer rubber compounds. A/Ts tend to be a cross between a street tire and an M/T. They are also generally accepted as better for use in sand. Generally, though, an A/T is considered a compromise for those that need a cross-functional vehicle - road manners and generally decent off-road capabilities. When purchasing a tire for off-road use, be sure to purchase an LT (light truck) rated tire.

Tire sizes:

Tires are generally sold and measured using 3 numbers. For example, "265/70/17" means 265mm wide, 70% sidewall ratio (sidewall height is 70% of tread width), and a 17" diameter wheel. To determine the tire's diameter, take the tread width, divide by 25.4, multiply by the sidewall percentage (70% means multiply by 0.70), multiply by 2, and add that number to the wheel diameter. For the aforementioned tire, the following would be the correct application of the formula:

(265/25.4*0.70*2)+17 = 31.6" tire diameter

You can also utilize our handy Tire Size Calculator.

Your next question will be... how big of a tire can I go with? What sort of wheel/tire combination can I use?

Your answer lies within the "Wheels / Tires" section of the forum. Specifically the following links are helpful. It's time for you to read:

But be careful not to under-gear your vehicle by increasing the tires beyond your differential gear ratio. You can get an idea of where your gearing and tires sizes stand by playing with our Gear Ratio Calculator.

Suspension Changes:

The second way of gaining lift, is by changing the suspension setup of the vehicle. This can entail using lift blocks, changing springs, or changing the entire strut assembly. Lifting by the suspension provides increased under-frame clearance, but does not increase the clearance under the rear axle, or the wheel-side of the front suspension arms.

Shocks are often upgraded when lifting a vehicle, but they do not provide any additional lift. Shocks however do control the range of motion of the suspension.

Suspensions are discussed within the "Lifts / Suspension" section of the site.

The following thread is particularly useful, and lays out the options fairly well:
The Complete Lifts and Suspension Accessories Thread

To determine which suspension lift is right for you, we recommend doing your own independent research by reading within the suspension section and the build threads (we'll cover the build threads more in depth in a bit).

You will find that in general, the suspension lifts are limited to about 3". This is because of the design of the front differential on our vehicle. The engine oil pan has a drive shaft running through it, which means we cannot shim the front differential downward, as is done on many other IFS (independent front suspension) type vehicles.

Body Blocks:

The final method of providing a lift is by putting blocks or spacers between the body of the vehicle and the frame. This is called a body lift. A body lift does not actually provide any additional under vehicle clearance, except directly under the doors and fenders. This can be useful to provide clearance for larger tires, or if your mission is to crawl over very large rocks. All of the options for body blocks are covered under the aforementioned "complete lifts and suspension thread".

Vehicle Recovery:

When you head off-road, you may ultimately get stuck somewhere. This is something you need to prepare for well ahead of time, as you may not have cell service, and you may be alone.

Instead of trying to cover all of this information in this FAQ, ORTB has created an article dedicated to this information:

Vehicle Armor:

One item we recommend heavily is vehicle armor. The oil pan and radiator hang down fairly low, and skid plates from one of our vendors are highly effective. As Ben Franklin once said, "An ounce of prevention is worth a pound of cure."

Build Threads:

As mentioned earlier, we have a build thread section. This is here as a resource for newbies and veterans alike. It's a place to share your build, and it's progress. It's also a place to learn. Being so, we have a strict content format to the threads in that section. Please be aware of this and read the rules prior to posting. And please note - there is no need to post a build thread for a stock vehicle.

Your homework, as a new member:

Since you've read this thread, you're already leaps and bounds ahead of where the pioneers of off-roading a trailblazer were when they began their quests. Use the data that is hosted on this website, and research your goals. Be sure to post up an introduction thread (here: viewforum.php?f=8), and let us know who you are, and what you're wanting from your truck. More than anything, enjoy the site.
8-) Build Thread | ExPo Build | YouTube Videos
Not all who wander are lost. -Tolkien
User avatar
Trail X
Posts: 9935
Joined: Mon Sep 07, 2009 10:22 pm
Location: VA, Roanoke
Name: James Downing
Vehicle Year: 2005
Vehicle: Chevrolet TrailBlazer
DriveTrain: 4WD w/ Aftermarket Locker
Rank: Expedition Guide

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