How To Fit 37" Tires On Your New Ford Bronco
The 2021+ Bronco has become a popular choice for off-road enthusiasts due to its rugged looks and versatility. In the last few years, it’s easily shown its merit as one of the most capable trucks you can buy - straight from the showroom floor.
One of the modifications that many Bronco owners immediately start thinking about is upgrading to larger tires, especially some coveted 37s. However, fitting 37-inch tires on a Bronco requires more than just swapping out the tires. In this article, we will discuss the steps (and parts modifications/upgrades) involved in fitting 37-inch tires on your brand new 2021+ Bronco.
KNOW WHAT YOU'RE WORKING WITH
With as many trim levels exist on the Bronco, there are some variables you’ll need to think about. Keep in mind that the stock tires on most 2021+ Broncos are generally 33s, so there is a significant difference in size we’re talking about here. And before you tell us - yes, we know there are some trims that come with 35s, and we’ve seen way smaller options floating around, too. Unless you were lucky enough to claim a Bronco Raptor, though, you’re going to need to do some work to make 37s work on your rig. It’s going to take some work to make 37s functional, no matter what your starting point is.
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CHOOSE THE RIGHT WHEELS
Choosing the right wheels is crucial when fitting 37-inch tires on a Bronco. You will need to select wheels with the appropriate offset and backspacing to ensure that the tires fit properly. The backspacing is the distance from the back of the wheel mounting surface to the inside edge of the wheel, while the offset is the distance from the center of the wheel to the mounting surface. In general, you will want wheels with a 4.5 to 5” of backspacing to push the tires out further from the body of the Bronco. This will provide the necessary clearance for the larger tires without impacting your ability to turn properly - and without rubbing.
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INSTALL A LIFT KIT
To fit 37-inch tires on a Bronco, you will need to install a lift kit. A lift kit will raise the height of the Bronco, providing the necessary clearance for the larger tires. There are several types of lift kits available, including body lifts and suspension lifts. Body lifts raise the body of the Bronco higher off the frame, while suspension lifts raise the entire vehicle, including the frame and suspension.
When choosing a lift kit, consider the amount of lift you need to clear the 37-inch tires. A typical lift kit for a Bronco ranges from 2 to 6 inches. A 4-5” lift is generally required to make 37s work on new Broncos, but you’ll need to check and make sure that’s going to work on your specific truck - keep in mind - we can’t know exactly what modifications you or any previous owner may have already made to your truck.
In our experience, the ICON Vehicle Dynamics Stage 3 Kit works well for fitting 37s, but it will still require some additional work - new coilover bump stops, travel limiters, and possibly more more.
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CUT MORE THINGS UP
Your truck’s factory crash bars will likely have to be removed, modified, or replaced. The team at ICON already has a high clearance crash bar available, and that’s definitely something we’d recommend if you need to modify or remove your factory crash bars. You may also need to trim inner fender wells, factory rock rails, or even your fenders.
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INSTALL FENDER FLARES
Fender flares are an essential component when fitting 37-inch tires on a Bronco. Fender flares will prevent 37s from rubbing against the body of the Bronco. There are several types of fender flares available, including bolt-on flares and pocket-style flares. Bolt-on flares attach directly to the body of the Bronco, while pocket-style flares create a wider fender flare by extending outward from the body. You’ll also keep the truck from flinging rocks at your truck, or other vehicles on the road. Fender flares (or in some cases, mud flaps) may be a legal requirement for your rig, depending on where you live, so don’t skip at least the research on this step. For maximum off-road clearance check out the IAG I-Line fender delete kit.
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RE-GEAR YOUR RIG
When upgrading to 37-inch tires, you will likely need (or at least want) to regear your truck. Re-gearing will compensate for the larger tires' additional weight and diameter, ensuring that the Bronco performs as it should. Without regearing, your Bronco will feel sluggish and have poor acceleration. A higher gear ratio will provide the necessary torque to turn the larger tires effectively.
For regearing, we’d recommend Yukon Gear and Axle components, but we’ll need to talk to you to get the specifics on your setup to make the best recommendations on sizing. Get in touch at (410) 840 - 3555 or shoot us an email at sales@iagoff-road.com, and we can help.
Take a look at more of our gearing options here-
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UPGRADE THE BRAKES
When fitting 37-inch tires on a Bronco, upgrading the brakes is essential. Larger tires require more stopping power, and the stock brakes will likely not be sufficient. Upgrading the brakes will ensure that the Bronco can stop effectively, even with the added weight and size of the larger tires. Consider upgrading to larger brake calipers and rotors, as well as adding a brake booster or master cylinder to improve braking performance.
For bigger brake kits, we trust each and every brand we carry, but like the gears we mentioned above, we probably need to get a bit more info on your rig and how you plan to use it to make the best recommendation to meet your specific needs. Give us a shout!
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CALIBRATE
After adding larger wheels and tires (and probably re-gearing, too), your speedometer doesn’t stand a chance at being accurate. You can calibrate your speedometer using an aftermarket programmer, or go with a Ford Performance tune, but unless you want to do math every time you’re on the highway (or risk a lot of speeding tickets), this is something you don’t want to skip.
Shop our tuning upgrades here-
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CHECK THE STEERING & SUSPENSION
Fitting 37-inch tires on a Bronco will put additional stress on the steering and suspension components. It is important to check these components and upgrade them if necessary. Consider upgrading the steering components, such as the tie rods to more robust versions to handle the increased weight and size of the tires. If you didn’t go with a full suspension lift, and somehow worked your way around the 37s anyway, you’ll want to consider upgrading the suspension components, such as the shocks and springs, to provide better support and handling whether you’re on or off-road.
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TEST DRIVE & ADJUST AS NEEDED
After completing all the necessary modifications, take your Bronco for a test drive. Check for any rubbing or interference between the tires and the body, as well as any handling or performance issues. Adjust as necessary to ensure that the Bronco performs as it should with the larger tires. You’ll also want to do some mild test driving to make sure any limiters you’ve installed are actually functioning properly - the last thing you want is to hit the dirt for the first time when you’ve got big plans, only to discover that you’re rubbing somewhere under your rig with every bump in the trail.
If you're needing to modify, take a look at our wheel well upgrades here-
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Fitting 37-inch tires on a 2021+ Bronco requires several modifications, some of which are fairly extensive - including choosing the right wheels, installing a lift kit, adding fender flares, re-gearing the axles, upgrading the brakes, checking the steering and suspension, and test driving and adjusting as needed. These modifications will ensure that the Bronco can handle the larger tires and perform well off-road.
Remember that some of these modifications require a certain level of expertise, and it may be best to seek the help of a professional mechanic or off-road shop to ensure that the modifications are done correctly and safely. With the right modifications, a 2021+ Bronco can become a powerful off-road machine capable of handling even the toughest terrain, but throwing 37s on your rig may not be as simple as you’d hoped. It’s all doable, but it’s a job you want done right - we’re happy to help you get there.
Keeping your rig safe and drivable when you’re out on the trails is just one part of a great wheeling experience, and IAG’s expertise can get you all the function you want - whether or not 37s are for you. If you’re looking for advice, need help with an install, or just don’t know what modification you might want to check out next, IAG Off-Road has the expertise you need. Give us a call at (410) 840 - 3555 or shoot us an email at sales@iagoff-road.com - we’d love to help!