What's the biggest tire I can fit..

@exploringyahweh

If your truck looks like it skips leg day or sounds like a buzzsaw every time you steer, this guide is for you! For more details on whether bigger tires are the right choice for you or not, please check out our previous article here.

One of our favorite types of emails asks, “What’s the biggest tire I can fit on my…?” While we’ll miss answering that question multiple times a day, we decided it was better to create a comprehensive guide instead. Most of the advice here is tailored to Toyota trucks and SUVs, but much of it applies to other body-on-frame trucks as well.

The Easy Stuff

Fitting a 31-33" tire on a Tacoma, 4Runner, or GX is generally straightforward and does not require many permanent modifications. The most significant change is usually a lift kit. For a 31" tire, a level kit may be sufficient. This raises the front of the truck slightly, correcting the factory stance where the front is typically lower than the rear, and provides enough clearance for a slightly larger tire. With a 3-4" lift, even larger tires can fit, although this is where modifications requiring more commitment may begin to appear.

The Really Hard Stuff

Once you reach the 33" range, a lift kit often needs to be combined with additional modifications: a bumper cut and a liner trim. If you are using the stock bumper, the lower portion of the front bumper usually needs to be cut for clearance. Factory mudflaps and plastics near the rear of the fender well may also need trimming or removal. Below are some examples of how the front bumper can be modified to allow for additional tire clearance:

@rithagram, @thrill_overland, @wvytaco

Additionally, behind the fender liner, there is a pinch weld with a seam that protrudes perpendicularly towards the tire. This will need to be hammered flat; usually it is pretty sturdy, so you really have to give it the beans with a sledge hammer. 

And to round things off, is the Body Mount Chop, or BMC for short. This is where the cab is bolted to the frame and, on most trucks, is a common area where big tires don't get along with the body too well. It is performed by cutting off a section of the protruding mount, and a new plate is welded in with a lower profile. You can look to spend anywhere from $450-600 on this job, and it's become popular enough to the point where companies have templates and weld-it-yourself kits. We prefer to take our trucks to a reputable shop that specializes in off-road fabrication.

The Body Mount Chop, or BMC, addresses a common issue where the cab is bolted to the frame and larger tires can interfere with the body. This modification involves cutting a section of the protruding mount and welding in a new, lower-profile plate. The cost for this job typically ranges from $450 to $600. It has become popular enough that companies now offer templates and weld-it-yourself kits. We recommend having this work done at a reputable shop that specializes in off-road fabrication to ensure proper fit and safety.

A BMC with a custom plate performed by @steve.ssahaus

The Really Really Hard Stuff

So you've gone off the deep end and want to put 35" tires or bigger on your truck. Well if you've gotten to this point, chances are you don't need to read a write-up on how to do it because you're probably already heavily invested into the whole off-roading thing (we hope). However, as this has become more and more popular and desirable, it's still worth covering some of the commercially available modifications out there. The most common of which is a Body Mount Relocation, or BMR for short. This modification involves removing the factory body mount entirely and replacing it with a smaller, purpose-built mount designed to provide additional clearance.

@drtfabrication relocation kit

Even with commercially available BMR kits, it is recommended to work with a reputable welder or fabricator. Precise measurements and quality welding are critical for maintaining proper body gaps and structural integrity. Beyond this point, most modifications will require custom fabrication and additional investment.

The reason we hesitate to recommend a specific tire size is that fitment can still be somewhat of a subjective process. Clearance and rubbing can vary between trucks, and even between the left and right sides of the same vehicle. While the modifications outlined above cover most scenarios for increasing clearance, there are additional factors that are often overlooked and should be considered when planning a larger tire setup.

Caster

Caster is the angle at which the wheel hub is reclined away from the shock tower, typically indicated in a positive degree value. The higher the value, the more clearance you will have from the rear of the fender well. Most trucks will have a limited amount of adjustment from the factory which, for the sake of clearance, should be set to the maximum positive value.

Wheel Offset/Width

Wider wheels, or wheels with a lower offset that sit further out, increase the scrub radius. This causes the wheel to move through a wider arc as it turns. Even with the same tire height, a tire mounted on a wider wheel will require more clearance at full steering lock

Loaded Weight

If your truck is intended for overlanding or carrying camping gear, it is important to measure clearances with the vehicle fully loaded. Camping and recovery equipment can add significant weight, especially with multiple passengers on board. For trucks used primarily for light off-roading or casual driving, this is less of a concern, but it remains an important factor for serious off-road setups.


A two finger gap while static is usually a good rule of thumb

Remember that on the trail, tires that clear on flat ground may still rub as the suspension moves cycles through its full range of motion. A small amount of rubbing is acceptable for some drivers, but not for others. As long as it is minimal, rubbing generally does not cause damage. For those who want zero rubbing, additional modifications may be necessary. Conversely, if your truck already experiences squeaks, pops, or cabin rattles while off-roading, you may be less concerned about minor rubbing.

We hope this guide provides a general overview of the considerations involved when increasing tire size. Always conduct your own research and determine what will work best for your specific setup. We hope this helps you plan your tire upgrades, and happy wheeling!