37s NO LIFT Jeep Gladiator Rubicon | Inside Line

• December 14, 2020
• Story By
  Ali Mansour

The 2020 Jeep Gladiator has proven to be an excellent build platform for those looking to adventure off-road and maintain a useable midsized truck for everyday life. One of our favorite features of our Gladiator Rubicon is the fact that is has massive wheelwells. Unlike other midsized trucks that would require a considerable amount of lift or fender modifications, tossing on something as big as a 35-inch-tall tire can be accomplished with no lift. This is something we’ve tested thoroughly in the past.

The wheelwells are so large in fact, it got us questioning if we could push the limits even further with a 37-inch-tall tire. So, we decided to try just that. Using a 37x12.50R17 Nitto Trail Grappler to give us one of the most true-to-size tires on the market, we set out to find just what would happen if we placed them under our stock (no lift) 2020 Jeep Gladiator Rubicon.

How did it all work? Well, for the full Inside Line scoop, we recommend you heading over to our YouTube channel to watch the entire breakdown. For those just hunting for the highlights, we’ve put them in the article below. Enjoy.

The Wheel Difference

We knew we wanted to run the Nitto Trail Grappler on this project as it’s our favorite go-to mud-terrain radial that does not sacrifice on-road comfort for off-road performance. Given the type of wheeling we have in store for this Jeep, we also knew that a true beadlock wheel was going to be worth the investment. We are running a 17x8.5 AEV Borah Dualsport wheel that is built with a +25mm offset and 5.72 inches of backspacing. While we wanted the high numerical backspacing for the assortment of benefits it provides, it would prove to be critical when cycling the tires under the Jeep.

Checking For Clearance

The first thing we did once the wheels were bolted on was cycle the steering from lock to lock to see if the tires would contact any of the suspension or frame components. Thankfully, we were in the clear. If we still had the stock plastic front bumper, we’re pretty certain the tires would have made contact. Having a stubby Arcus series front bumper from Rugged Ridge made a huge difference in just being able to hit the road without an issue.

Flex Test

Rather than speculate just what would happen when we disconnected our Rubicon’s front sway bar and twisted the Jeep up on the trail, we took a trip to Low Range 4x4 to put our Jeep on the shop’s 30 degree RTI ramp. With the sway bar disconnected, we drove onto the ramp until the rear tire lifted off of the ground.

Up Front

With the front axle resting on the bumpstop, we knew there would be contact with the front fender. Thankfully, it wasn’t enough to do any damage, just merely put a little extra pressure on the plastic fender. While we were able to make it up the ramp with ease, there was no doubt that a hard articulation scenario like this would equate to series fender interference on the trail.

Out Back

The big surprise we found on the ramp was that the rear wheelwell swallowed up the Trail Grappler with ease. While there was some pressure on the inner portion of the fender line, it wasn’t enough where it would do damage. This is where the 5.72 inches of backspacing really came into play as any less the tire would have contacted where the fender begins to sweep down.

About That Offset

While the RTI let us know that hitting any hard trails wasn’t going to be in the cards, we continued to drive on this setup daily. From powering over speedbumps to taking the kids to the beach, we were blown away at how well it worked. We accredit a large part of this success to the +25mm offset as the modest spacing of the tire outside of the fender gave use just the right amount of clearance.  

What About The Spare Tire?

We still haven’t figured out our long-term solution for mounting the spare tire. For now, we found that it works fine strapped on our AA Products bed rack (learn about that here) or we can just toss it in the bed. On the stock wheel, we’ve had good luck mounting a 37 under the bed. However, in this configuration, we found it hits the rear track bar in the stock mounting location.

Does It Work?

With our specific wheelset and Arcus front bumper, we can say with a fair amount of confidence that this 37 and no lift combo works fine on the street. While we did do some very mild off-roading, put the Jeep on the RTI ramp showed us that this setup isn’t going to work on the trail. Now, if we were willing to either modify the front fenders or ad a bumpstop extension to the front axle, we think this setup could work off-road. Don’t worry, we will be looking at all of those options more closely very soon.

While we go into this more in depth in the video, moving up to a 37-inch-tall tire has definitely opened up a few more issues that we will need to deal with. For starters, our fuel economy took a big hit—dropping from around 16 mpg to a little over 14 mpg. Also worth noting is that we now rarely see Eighth gear. At highway speeds, we are losing out on Seventh frequently as well. What does this mean? Quite simply, we feel strongly that it needs higher numerical differential gears.

We will be diving into all of these challenges in the coming months. At the end of the day, the Gladiator wheelwells are something to rejoice. Yes, 35-inch-tall tires and no lift is still the better option. However, we are excited to continue our build journey with the Gladiator and see just how well we can push this platform to best fit our needs.