One of the simplest and most popular modifications to any off-road vehicle is the installation of bigger tires. While they can be helpful in many ways, they can also add stress to the vehicle’s drive train. Let’s check out a few of the pluses and minuses of bigger tires.
Better off-road capabilities
Because the tires are larger, they have the ability to go over larger objects. Also, most large off-road tires have a more aggressive tread, which means more grip on the trails and in the mud. They can be aired down to both soften the ride and provide even more traction whereas a smaller tire is very limited in that area.
Raises vehicle height
When you go from, for example, 29″ tires to 35″ tires, the bottom of the rig itself will sit 3″ higher. 35-29 is 6, and since half the tire is above the axle, we divide 6 by 2 and come up with 3 inches. A little added height almost always helps off-road.
More aggressive look
Let’s face it: rigs with huge tires just look cool, and that’s a fact. You’ve seen the mud trucks on 40-plus-inch tires. They’ll widen your eyes. Of course, 44-inch Boggers aren’t really practical for the street, but they sure do work well off-road and they look killer to boot.
Harder on brakes
Because a larger tire has more mass, it’s heavier. This causes the brakes to work harder than before to stop the rig, which can become problematic and dangerous. Most four-wheel drive braking systems are good for 35″ rubber and after that, brake modifications are highly recommended. The brakes were designed for the stock-sized tires. More rotating mass means more strain.
Harder on axles
Picture holding a flower in your fingers and spinning it via the stem. Now picture that same flower, only it’s 39″ across. Can you see why it would be harder to turn from the same center point? For that reason, serious off-road enthusiasts upgrade to thicker axle shafts with more splines. Chromoly axle shafts can withstand a heck of a lot of strain.
Harder on steering boxes
Bigger tires will have more surface area contacting the ground than stock tires. Therefore, there is more friction each time the wheels are turned, which equates to more strain on the steering box. Jeeps in particular are known for ripping the boxes off the frame when big tires put a stress on them over time.
Big tires are more expensive
Have you priced a set of new 35s lately? Whew! We aren’t talking a few dollars. Of course, used ones are always available but you won’t get the benefit of full tread, most likely. There’s also the question of how to carry a full-size spare in the vehicle. A 35″ tire never fits in the stock location.
There’s also the question of lift. To fit sizeable tires on your rig, you’ll probably have to install a suspension lift kit and/or a body lift. Suspension kits are almost never cheap.
There are more pros and cons, but I believe I’ve hit the major points. Remember, your rig may not benefit at all from those cool-looking 38s. Most Jeeps do great on 33s, and a full-size can do amazing things with 35s.