Buying new tires for your Jeep, SUV or Truck? How do you know the right size to buy? Why do some tires have big numbers like 255, 265 or 285 while others are 30, 32, 33, 35’s?
In this article we are going to breakdown the difference between a 285 and 33 inch tire because those are two very popular tire sizes. I happen to have new 285 tires on my 2006 Jeep Wrangler Unlimited (LJ) right now (cover photo).
Are 285 Tires Equal (the same) To 33’s?
As a quick rule of thumb, assume the 285 tire is equal to the 33-inch tire. However, the 285 is slightly smaller than the 33 inch tire. the 285 tire has a diameter of 32.832” in comparison to the 33” tire. This means that the 285 tire is slightly smaller than the 33”. Additionally, you need to check each tire manufacturer’s specs as there is variability in the 285 and 33-inch tire offered by each tire maker (crazy, I know).
Every tire manufacturer in the world has its tire molds. This means that without a set pattern in the industry, the actual diameter is different from one manufacturer to another.
This makes the 285/75/16 to be regarded as the metric size for 33” that is accepted globally. The two sizes are extremely close but the 33” is slightly larger.
The only way of finding out the actual diameter of a tire is by visiting the website of the manufacturer and getting the manufacturing specifications from them.
How much lift do I need to fit 33-inch tires?
Getting 33” tires on any off-road vehicle will significantly improve its ground clearance, improve off-road capabilities and provide better on-road and off-road traction.
Unfortunately, depending on your vehicle’s model, fitting can prove to be a complicated procedure and isn’t as straightforward as you think. We shall be discussing how much lift you need and any modifications that need to be done in order to fit the 33’s to your vehicle.
Most vehicles with an independent front suspension need a 2.5 to 3” minimum lift in order to fit 33” tires. This, however, is often accompanied by some fender and body mounts trimming in order to fit the 33” tires. As for vehicles with a solid front axle, fewer modifications are required in order to fit these tires.
The single and easiest ways of improving ground clearance are fitting bigger tires onto your vehicle. The extra inches are essential in clearing bigger obstacles when you are driving off-road.
For 4WD vehicles with an independent front suspension (IFS), however, there are several limitations because there are more components in the suspension. For solid front axle (SFA) vehicles, it is much easier and less complicated.
To allow complete turning of the front wheel without scrubbing of the fenders, full articulation when off-road and complete functioning of the 33” tires, additional modifications are required. Some vehicles like the Jeep Wrangler come with wider and bigger wheel arches straight from the factory.
The opposite, however, is true. Some come with much smaller clearances and square-shaped wheel arches, which are a limitation. Additionally, some cars sit naturally sit higher off the ground when others seem to hover just above the ground.
The risk of damaging your CV when off-roading is relatively high in Independent front suspension vehicles when you exceed the 2.5-3” lift because the angles on the CV are really high.
In order to fix this, you will have to install a differential drop kit in order to lessen the CV angle when you go above the recommended 3 inches.
Additionally, you will have to install an aftermarket UCA that is adjustable in order to take the pressure off the upper ball joints. This is because once you go above 3 inches, the angle of the UCA is really steep, which limits downward travel.
You will also have to do the same to the stabilizer links. The higher you go on an Independent front suspension, the more expensive the modifications become.
Apart from Independent front suspension and solid front axles, what are the other factors to consider before fitting 33’’ tires?
Sizes of wheel arches
Wheel arch sizes vary from one car to another. This will often be the difference between heavy bodywork modification and a light trim. In most cases, however, only little trimming is needed in order to fit 33” tires.
In order to avoid scrubbing at full lock, a little BMC is also required. In newer trucks like the Ford ranger or the F150, complete removal of cutting away of the crash bars is also necessary
This basically means cutting away part of your beloved vehicle. Modern 4X4 vehicles like Tacoma and Ranger come with plenty of safety features that are built into the chassis of the vehicle. This poses a challenge when installing larger tires.
A good example is the third generation Tacoma. In this particular vehicle, the mount of the body protrudes by a substantial amount. This restricts the installation of bigger tires without modifying the body mount.
This can either be done by cutting, welding, painting the mount that exists, or purchasing an aftermarket body mount. This process might be tasking if you are doing it alone and is even more challenging if you are not familiar with the workings of a welding machine or a grinder. It is therefore wise to seek the services of a custom shop.
Wheel offset and backspacing
By definition, Backspacing is the distance between the mounting surface of the hub and the wheel’s inside edge. In order for you to increase inside wheel clearance, the backspacing must be decreased.
Offset, on the other hand, refers to how outward or inwards your wheels are sitting inside the wheel wells. Wheels usually come with a negative, zero, or positive offset.
When a wheel has a negative offset, it means the imaginary center line is towards the wheel hub, making the wheel develop a profound dish effect. When a wheel has a positive offset, the imaginary center line of the wheel is outwards away from the hub.
Arch and fender trimming
Depending on how wide the tire is, backspacing and wheel offset is often accompanied by arch and fender trimming. 33” tires are wide tires and therefore require more space inside the wheel arch to prevent rubbing, especially when maneuvering in off-road situations.
If you decide to fit bigger tires into a normal-sized wheel arch without lifting your truck, you will have to chop off a huge part of the arch plastic and inside the fender to allow the huge tires to fit inside the arch.
How much lift do I need to add to my 3rd Gen Tacoma to fit 33” tires?
First of all, you need to do some body mount modification combined with a little arch trimming for the tires to fit. After that, you will need a 2.5-inch lift and -12 negative offset rims for the setup to work.
The additional modifications on the body include pinch weld bending and welding and cutting of your vehicles body mounts. At the back of your vehicle, there is little to do as there are no clearance issues. You just need to install the negative offset rims.
For improved clearance, you may consider wheel arch trimming. If you choose to do this, you will have to say goodbye to your wheel arch liners.
When turning, it is essential to note that the front wheels not only move right and left but also move backward and forward. This is the reason why we trim wheel wells to avoid rubbing.
The only difference between 33’’ and 285 tire sizes is the difference in measurements, however ultimately, the 33” is slightly bigger than the 285 tire. You can now go and get the bigger wheels with no doubt in you and give your car more off-road capabilities.