Choosing tires can be a daunting endeavor. Often they are considered the most important part of a vehicle, as they are the only point of contact with the ground.
There are a few things to decide on.
- Tread Pattern (Mud-terrain vs. All-terrain)
- Tire Diameter
- Tread Width
- Weight Rating
Depending on your terrain and normal travel paths, you may opt for an aggressive mud-terrain pattern or a more mannered all-terrain. Of course, there are many options that full the spectrum between the two main categories, but in general terms, there are 2 main options. The M/T option gives better traction in mud and most off-road situations than the A/T, but the M/T notoriously are noisier and less fuel efficient.
This decision is not only affected by the lift and clearance you have, but also the gearing. This is a bit of a balancing act. You want a large tire to gain more clearance and roll over obstacles easier. However you don’t want to decrease the thrust to unbearable levels. As a tire gets larger, the torque at X RPM stays the same, thus the available thrust will decrease. Through the years I’ve come to the conclusion that 32″ tires are perfect for my needs off road, and don’t make thrust levels unbearable to the point of constant downshifting on the interstate.
There are long standing debates on the proper tire width for off-road/overland vehicles. Many of the crawling crowd will go for 305mm width or beyond for traction purposes. Many of the overlanding mindset will choose a thinner tire (235-265mm) for fuel efficiency. Since our mindset is more aligned with overlanding – here’s a link to a good discussion on tire width that concludes that skinnier tires are generally the way to go: http://www.expeditionswest.com/research/white_papers/tire_selection_rev1.html. I ended up going with a 255mm width tire for the Trailblazer.
For a light truck tire, the load rating is given by a letter (B, C, D, E, or F) depending on sidewall plies and directly relate to max air pressure ratings. I find the load range C to complement the Trailblazer well. Others have had luck with D and E. D and E are known for being somewhat more resistant to sidewall damage, especially when aired way down.
I ended up deciding on BFG Mud Terrains. The size, 255/75/17, are commonly found on Jeep Rubicons as OEM equipment, so ultra-low-mileage tires are fairly easy to find for around $125 each. I’m on my second set of these tires, with the first set wearing amazingly well – maintaining good tread depth through 55k miles. I expect the tires could go to 70k easily. They are a slightly special tread pattern, denoted by “DT”, pictured at right.