Section 3: Tires
Good Tires are Mandatory
The very first thing that you need to do before attempting any offroad driving is to upgrade your tires. Street tires are not designed to withstand the sharp stones, rocks, and other hazards that you will encounter once you leave the asphalt. Nor are street tires structured to be driven at deflated air pressure such as 15-20psi.
Your stock Jeep, Toyota, or other 4x4 SUV may have better than (street) average ground clearance, four-wheel drive, and some factory equipped goodies – but those OEM street rated tires might not be conducive to the rigors of a non-maintained back country trail.
If the dealer upsold you to a set of factory equipped, so called “AT” tires – you need to ask around and find out if those tires really are heavy duty, All Terrain, offroad rated tires or just low end models that barely qualify as AT.
When we bought our 2021 Jeep Wrangler Sahara, we opted for the All Terrain tire package. They were great for the daily commute across Los Angeles, and even for our first forays “off road” on some county-maintained dirt/gravel routes.
It was only after we became active with a jeep club that we realized our tires would not suffice. We replaced them after 5 months with a set of beefy Micky Thompson Baja Boss 33 inch x 12.5 inch All Terrain “big” tires. Not only did our Jeep look macho with the new shoes, but we immediately appreciated the improved traction and smoother ride when we hit the trails.
Helpful Tip: If you want to immediately upgrade from OEM street tires to at least stop-gap AT tires – check online market places such as Craig’s List. Lots of Jeep owners quickly ditch their original (Rubicon) and OEM AT tires in order to replace them with expensive heavy duty or oversize offroad tires. These are referred to as “take offs”. The marketplace is full of them, they are bulky to store at home, so the asking prices are extremely cheap.
We eventually sold our “take offs” for only $100, for the entire set of five. We just wanted to regain the space in our garage, and were happy to see them go to someone who really appreciated getting them until they too could afford new rubber for their jeep.
Let’s learn about tires
All Season tire
First, let’s discuss the difference between All Season vs All Terrain.
I think that this is the most misunderstood concept that most beginners harbor. These two types of tires are very different from each other.
All Season are street tires, designed to be effective in light rain and light snow, and in climates ranging from moderate winter through moderate summer. The idea is that if you are only going to have one set of tires throughout the year, these are what you would buy.
If you lived in extreme cold climates, you would have winter tires during those months and then change to a summer or rain tire for the other months. The winter tires are optimized for the cold so that the rubber treads do not become brittle. Snow tires have more aggressive tread patterns for better traction; some tires even have metal studs embedded to dig into ice.
All Terrain tire
All Terrain tires are not unlike All Season in that their chemistry is designed for all year use in moderate climates. But that is where the similarity ends.
All Terrain have much more aggressive tread pattern, with an emphasis for greater traction in loose media and at slower speed than your typical highway tire. The tread pattern is not only designed to grip dirt and loose media better, but also to eject caught media from the treads as the tire rotates. The hardness of the rubber is a compromise for use both on highway as well as offroad.
Some AT tires are snow rated. The M+S designation indicates good performance rating in snow or mud; but the triple peak symbol indicates better performance ratings in snow. I call your attention to this if you live in a snow prone environment, because some “chains required” areas only exempt 4x4 vehicles running triple peak rated tires.
AT tires have deeper and more aggressive treads than regular tires. They also have stronger and thicker sidewalls, which protect against slashes coming from horizontally protruding hazards. Think of the Titanic sliding against the iceberg. AT tires also have thick reinforced shoulders where the flat tread meets the sidewall.
AT tires are built to run offroad at deflated air pressure levels. The reinforced shoulders and stronger sidewalls prevent tire buckling and losing their bead mount on the wheel (the correct term for the metal rims that the tire mounts onto is wheel, by the way). The relative strength of the sidewall (rated vehicle load weight capacity)is indicated by the letter rating on the tire, so a tire rated E is beefier than a tire rated C.
A lot of car manufacturers may offer AT tires as an optional upgrade, or as part of a special performance package. The tires will be branded from a well known tire company, but more times than not, these OEM tires are bottom of the line compared to the expensive AT tires most of the offroad community run. There are exceptions, so do some research. It might make better economic sense to skip the AT tire upgrade from the dealership and just to purchase high quality AT’s from a tire store.
All terrain vs Mud terrain
When you shop for tires, you will be offered a choice of All Terrain or Mud Terrain. So which one is better to get?
Both types are suitable for highway as well as offroad driving, but there are some subtle differences.
AT tires have a more balanced mix of tread blocks, which makes them slightly better on highways.
Mud Terrain tire
MT (mud terrain) have a more aggressive tread pattern, along with larger gaps in between the tread blocks, giving them better performance in mud and dirt. However, they do run noisier on paved roads. MT’s may or may not be snow rated, and are usually not recommended for cold, snowy conditions.
AT rubber is stiffer than MT, so AT tires usually have a greater lifespan (up to 50k miles).
But the softer tread of MT gives them slightly better traction on rocks and trails. The softer composition does reduce their lifespan if you drive a lot on paved surfaces, so they may not be the best choice if your Jeep is your daily driver.
MT tires usually cost a bit more than AT’s.
MT tires are generally more popular with hardcore rock crawlers, since they do perform slightly better on most trails.
AT tires tend to be more common amongst Intermediate level offroaders, who drive their jeeps on paved roads way more often than the occasional trip into the boonies.
R/T tires (Rugged Terrain) are hybrids. Somewhere in the middle between AT and MT. They are more aggressive than AT’s, but harder rubber than MT. So a bit noisier than AT’s on the highway. Not as long lasting as AT’s. But better traction on dirt. I think it is more about marketing than actual distinctions, so do your research when making a selection.
Tire sizes
Forgive me for not discussing other 4x4 vehicles, but if you are driving something other than a jeep, it is easy enough for you to find the specifics of your car.
Most of the standard size OEM tires (at least for Jeep Wranglers) range from 28 to 31 inches in diameter (ground to top of the tread). Those tires also are on the narrow side, often from 8 to 10 inches across.
When you upgrade to bona fide offroad tires, you are usually looking at 33 to 37 inches.
For the purposes of this discussion, I am only going to use layman’s terms in describing tire sizes: diameter x width x wheel/rim size. Tire manufacturers often use a more complex metric equation based on width, sidewall height, and wheel size – but that really requires using a conversion chart or doing some serious math. Therefore, I am keeping this simple. If you want to learn more about the metric numbers, I recommend just going to any major tire manufacturer’s website.
If you are driving a stock (unlifted) Jeep, the largest offroad tire that most jeep trims can accept is 32-33 inches in height/diameter. Depending on the tire manufacturer, the physical measurement may be a few fractions of an inch different than the advertised number, not that it matters in the real world.
Larger tires will increase your ground clearance by raising up your axles. Note that the increase is only half of the total diameter difference. Example, if you were running 29 inch original tires, and upgraded to 33 inch tires – that is a 4 inch difference in total tire height, but your axle (in the center of your tire) only raises 2 inches. If you were originally on 31’s, then your axle only raises 1 inch.
Sahara with 33 inch tires. Compare to 35 inch tires on other jeep.
Moving up to a larger diameter tire usually means that you are also increasing the width of the tire. For example, my Micky Thompson AT’s were 33 inches in diameter but 12.5 inches across the treads. My Wrangler Sahara had plenty of wheel well height (Sahara’s come slightly lifted from the factory), but we discovered that tight turns caused the inner edge of the rubber to make contact with the side of the wheel well, on account of the tire’s fat width. The rubbing was slight, and we lived with it for a while, since extremely tight turns were rare.
When we upgraded to the 33 inch tires, we chose to keep the original wheels (rims) which were centered for a narrower tire.
There are two solutions to eliminating the rubbing. Somehow, the new tires had to be pushed further outward. We could replace the OEM wheels with new wheels that provided an offset mounting point, thus extending the outer edges of our tires slightly beyond the fenders and maintaining proper clearance on the inside edges. But new wheels do not come cheap, and we had just spent a lot of money on five tires.
The other solution was to just install inch and a half metal spacers between the axle and the wheels. Easy and inexpensive, but make sure that the install is properly torqued.
We originally chose 33 x 12.5 tires because we used our jeep for daily commuting, and felt that size was a good compromise between offroad capability and highway efficiency.
Sahara with 35 inch AT tires, 2.5-inch lift
Recently, we upgraded again to 35 inch AT tires. Now that my wife and I are fully retired, we are no longer concerned about a daily commute. Our jeep is primarily a recreational vehicle (we have a Subaru Wilderness as a daily driver).
The difference in ground clearance from 33 to 35 is only 1 inch. But the circumference of the new tire is much greater than the 33, and way greater than 29-31. So moving up to 35’s greatly increased our traction and made a very significant improvement offroad.
“Even though it is only 2 inches larger than 33’s, we were surprised at how much better the 35’s performed offroad. Much better traction, less bounce, and way better at rolling over obstacles.”
Our jeep had been lifted to 2 ½ inches, so the added height of the 35’s was no problem. If you drive a stock vehicle, you will require some lift in order to accommodate anything taller than a 33.
Again, depends on your particular vehicle. But most (not all) jeeps can handle 33 either with no added lift or just an inch or so. 35 will definitely require a lift.
Lifts do not increase the height of the axle, but do increase the height of the chassis and passenger compartment above the axle.
Because of the greater weight and circumference of the 35’s, we opted to purchase new wheels to go with them in order to prevent any rubbing. The new wheels add to the look of our jeep, and provide a built-in offset that is a more permanent solution than spacers.
Before just rushing out and upgrading to 35’s, be aware of the negatives.
Your vehicle needs to be lifted so that there is ample room for the tires to bounce around in the wheel well.
Reinforced tailgate hinge and spare tire support
35 inch tires are not only larger, but they are considerably heavier and protrude out more. That means that your rear (spare) tire holder may need to be raised up or replaced (depends on the tire clearance of your rear bumper) and your tailgate hinges will need to be upgraded to handle the added weight.
The additional weight of five tires will take a toll on your miles per gallon.
Because the circumference of 35 inch tires is significantly greater than your original factory tires, it will require recalibration of the speedometer and transmission. That is a computer setting, and can be done using an aftermarket electronic module, such as the Tazer Mini.
We installed the Tazer Mini on our Sahara (it just snaps into a socket under the dashboard), and it provides lots of custom settings in addition to tire calibration.
35 inch tires are the most common in our jeep club.
37 inch?
For those who take offroading very seriously, there are 37 inch tires and even larger ones than that. 37’s climb over obstacles without a hiccup.
Besides being very expensive and very heavy, 37’s definitely require plenty of lift. Your axles need to be extra strong to deal with the torque -- nothing wimpier than Dana 44’s, but beefier is better. Not only do you need to recalibrate the computer settings, but you will need to physically upgrade the gearing in your differentials as well.
37’s are not necessary for Beginners.
So the question you are probably asking is “Which size tires should I purchase?”
It really depends on what the role of your 4x4 is in your daily life, and how serious you want to become involved in offroading.
If your vehicle is your daily driver, and you put on a lot of mileage – 33’s are better than 35’s in terms of gas mpg. 33’s are very capable offroad, if you anticipate doing the easier trails (difficulty rating 1-3) and not getting heavy into rock crawling.
However, 35’s are superior for offroad. Upgrading to them does entail other mods to your vehicle, in addition to the cost of tires & wheels. You will need a lift, reinforced spare tire holder and reinforced tailgate hinges, and your onboard computer needs to be re-programmed or calibrated for the new tire size so that the transmission & speedometer are set for the larger diameter rubber. Upgrading to 35’s is not cheap.
When you purchase a set of tire for offroad, be they 33 or 35, you do need to get a complete set of five tires. Your spare must be the same diameter as your other four, or it will wreck havoc on your vehicle. We recommend always doing a full, five tire rotation so that all of your tires will wear evenly and to maximize overall tire life. Chances are, a few years from now, the same make/model of your tires may no longer be available, so why try to conserve that spare.
