Fitting 37 Inch Tires on a Leveled Chevy Silverado
Fitting 37-inch tires on a Chevy Silverado is usually synonymous with one thing: a massive, bracket-style 6-inch lift kit. But at 3D Offroad, we’ve always prioritized function, a low center of gravity (LCOG), and pulling off what others call "impossible."
We partnered with the legends at Built2Wander to take a leveled Chevrolet Silverado 1500 and achieve the ultimate stance: 37x12.50R17 Nitto Recon Grappler A/T tires on a Bilstein suspension leveling kit.
Achieving this uncommon feat required far more than a "bolt-on" mindset. It demanded precision fabrication, a drivetrain overhaul, and a bulletproof transmission. Here is the exact blueprint for building a leveled Silverado on 37s that actually performs.
The Secret Sauce: The "Extreme NorCal Mod"
Most Silverado owners are familiar with the standard NorCal mod (also known as the "fender mod"), which involves trimming plastic and perhaps a small pinch of metal to clear 33s or small 35s.
To fit full 37-inch tires on a leveled truck, a simple trim won't suffice. At full lock or under suspension compression, those massive Nittos will destroy the factory wheel wells.
To solve this, 3D Offroad performed what we call an "Extreme NorCal Mod." This isn't just trimming; it’s surgery.
We cut out the entire factory vertical pinch seam located at the rear of the front wheel well.
We fabricated custom fill panels and re-welded the body structure back together to gain a critical 2+ inches of clearance.
The area was then sealed, painted, and finished to look OEM, ensuring zero rubbing while maintaining the truck's structural integrity.
Suspension: The Bilstein 6112 & 5160 Setup
A low-quality level won't work here; we needed performance that kept up with the stance.
We installed the Bilstein B8 6112 Leveling Kit coilovers up front. The 6112 utilizes a 60mm digressive piston and adjustable spring seats to provide up to 2.75" of lift, improving ride quality and increasing front wheel travel.
To match the performance of the front, we utilized Bilstein 5160 Remote Reservoir shocks in the rear. The remote reservoir significantly increases oil capacity for better heat dissipation, ensuring fade-free performance during extended off-road use.
Drivetrain & Transmission: Making it Drivable
The biggest mistake people make when jumping from a stock tire (31-33") to a 37-inch tire is ignoring the drivetrain. Adding massive rotating mass destroys the truck's powerband and destroys the transmission.
Re-Gearing to 4.56
To regain the factory "pep" and take the stress off the motor, we re-geared both axles using 4.56 gears from Revolution Gear & Axle. A 4.56 ratio is the "sweet spot" for 37s on this platform, returning the truck to its optimal RPM range for both highway cruising and slow trail work.
8L90 Transmission Rebuild & Billet Torque Converter
The Chevy 8L90 8-speed transmission is known for running hot and having torque converter issues, even on stock tires. To "bulletproof" this build, 3D Offroad performed a complete 8L90 transmission rebuild.
Crucially, we installed a high-performance billet torque converter. This converter features an upgraded clutch pack that eliminates the common "shudder" and handles the increased torque load of the 37-inch tires without breaking a sweat.
Wheel & Tire Specifications: Offset Matters
Finally, to get the stance and clearance correct, we prioritized wheel offset.
Tires: Nitto Recon Grappler A/T (37x12.50R17)
Wheels: KMC Wheels GRS (17x9)
Offset: 0mm
Why a 0mm offset? A negative offset (-12mm, -24mm, etc.) pushes the tire out too far, increasing the "scrub radius" and causing severe rubbing on the body. A 0mm offset provides the perfect balance: widening the track for stability and aesthetics while keeping the tire tucked enough to clear the body during steering.
The Final Verdict: Uncommon Feat, Ultimate Reward
Fitting 37s on a leveled Silverado isn't easy, but thanks to this incredible partnership with Built2Wander, Revolution Gear & Axle, Bilstein, KMC Wheels, and Nitto, we created a capable, reliable, LCOG trail machine.
Want this setup on your truck?
📍 Visit us at 3D OffRoad for all the parts used in this build! 📞 Contact 3D Offroad for specialized fabrication and installation.
Watch the Full Build Video Here!
