Jeeps carry the spare on the back because the original 1941 Willys MB had nowhere else to put it, and every design decision since has kept it there. A flat-floored, short-overhang 4x4 with a removable top has no under-floor spare well and no cargo hold to give up, and a part-time 4WD driveline wants a full-size spare that matches the other four tires exactly. Once the CJ-2A added a tailgate in 1945, the spare bounced onto the body side for four decades before coming back to the gate, where it has stayed on every Wrangler built since. It is one of the few pieces of Jeep design that is equal parts engineering necessity and brand identity.
Here is the actual sequence, with the parts most retellings skip.
1941: the flat rear panel was the only real estate left
The Willys MB and its Ford-built twin, the GPW, were built to a brutally tight spec: an 80-inch wheelbase, minimal overhang, a flat cargo floor, and a solid rear tub with no opening. No trunk, no under-body carrier, and no room in the passenger compartment once you loaded the thing with soldiers and gear.
So the spare went on the outside, bolted to the flat rear panel through a dedicated carrier bracket. Restoration parts catalogs still list it that way today, including the detail that the carrier itself changed from an early two-bolt style used through 1943 to a three-bolt style for 1944 and 1945. That is a small thing, but it shows the mount was actively engineered, not just tacked on.
If you want the full story of how the MB came together out of the Bantam, Ford, and Willys prototype competition, we covered that in our history of the Jeep.
1944 and 1945: the tailgate arrives and pushes the spare aside
The tailgate changed everything. Willys was already planning a civilian Jeep before the war ended, and a farm and utility vehicle needs to be loadable from the back. Jeep historians at CJ3B.info date the first experimental tailgate to 13 March 1944, part number E-50916, fitted to the CJ-1 prototype. It was revised for the CJ-2 as E-51213, the version with the raised center pad stamped "JEEP."
Cut a door into the rear panel, and the spare tire carrier no longer has a panel to bolt to. When the CJ-2A went into production in 1945, the spare moved to the passenger side of the body, ahead of the rear wheel on early builds and behind it on later ones. That side mount stuck around for a long time. Reproduction brackets for it are still sold under fitment ranges spanning 1945 to 1983.
The rear of a Jeep was doing a lot of communicating in this era. If you have ever wondered why "4 WHEEL DRIVE" was stenciled across the tailgate itself, that is a story with its own timeline, and we dug into it in our 4 Wheel Drive tailgate stencil history.
1951: the Army put it back on the tailgate first
This is the part almost every version of this story leaves out. The tailgate spare did not start with the Wrangler. It started with the military.
The Willys M38, the militarized CJ-3A built from 1949 to 1952, mounted its spare high on the passenger side of the tailgate. To make that work, the tailgate stamping itself had to change. CJ3B.info records that on 4 May 1951 the tailgate flange picked up four cutouts to clear the M38 spare tire carrier hardware and the M38 rear seat. Those cutouts then stayed in civilian tailgate stampings for years afterward, long after the military carrier they were designed for was gone.
So for a stretch in the early fifties, you could buy a Jeep with the spare on the gate and a Jeep with the spare on the fender, and the tailgate stamping was the same either way.
The CJ decades: the side mount becomes the look
Through the CJ-3A, CJ-3B, CJ-5, CJ-6, CJ-7, and CJ-8 Scrambler, the body-side spare was the familiar civilian arrangement. It kept the tailgate free to swing, kept the spare low and easy to reach, and gave the CJ that slightly asymmetrical profile people still recognize instantly.
It also had real drawbacks. The carrier hangs off sheet metal, so a heavy spare works the quarter panel every time you hit a whoop. It eats into the space where you would want a rear-quarter graphic or a fuel filler. And on a narrow trail, a tire sticking out past the body line finds things.
1987 onward: back on the gate for good
By the time the Wrangler YJ arrived for the 1987 model year and replaced the CJ-7, the spare had moved onto the tailgate, and it never left. YJ, TJ, JK, and JL have all carried it there. Structurally, it is a better answer than the side mount because the load goes into the gate and its hinges rather than into a quarter panel, and because it sits centered, so it doesn't widen the vehicle.
It also became non-negotiable. When Jeep engineered the backup camera for the 2018 JL, the company put it in the center of the spare tire carrier, and its head of product safety explained the reasoning plainly: the Wrangler always has a rear-mounted spare, so that was the one spot where the camera would not be blocked no matter which wheel and tire package the truck left the factory with. The camera housing doubles as the cover that locks the spare to the carrier. That is a company designing around the spare instead of around it.
The JL made the swing gate a load-bearing part
The JL is where the rear-mount stops being traditional and starts being a hard engineering constraint. Jeep put the 2018 Wrangler on a lightweighting program that used aluminum for the doors, hinges, hood, fender flares, and windshield frame, and made the swing gate out of magnesium. Then it kept asking that gate to hold more.
The clearest proof: when Jeep launched the Xtreme Recon package in July 2021, it gave the four-door Rubicon and Rubicon 392 factory 35-inch BFGoodrich KO2s, and listed "swing gate reinforcement" right alongside the tires, the beadlock-capable wheels, the 1.5-inch lift, and the 4.56 gears. You cannot just bolt a bigger spare to the back of a Wrangler and call it done. Jeep could not either.
Worth noting what that package still achieved with a full-size 35 hanging off the back: a 40.4-degree departure angle and 12.9 inches of ground clearance. The rear mount costs you less than people assume, because the tire sits above the bumper line rather than under the frame.
The Gladiator is the exception that explains the rule
Here is the tell. The 2020 Gladiator is a Wrangler from the B-pillar forward, and Jeep did not put its spare on the tailgate. Per Jeep's own launch material, the Gladiator's full-size spare mounts under the bed, behind the rear axle, in a carrier rated to hold up to a 35-inch tire.
Why the change? Because for the first time since 1941 there was somewhere better. A five-foot steel bed on a longer frame gives you real estate behind the rear axle that a Wrangler simply does not have. The Gladiator's tailgate is a damped, power-locking truck tailgate that stops in three positions, and hanging 80 pounds of spare on it would have wrecked all of that.
Which means the rear-mounted spare on a Wrangler is not nostalgia. It is what you do when there is no other place. The moment Jeep had another place, it used it.
Why a Jeep needs a full-size spare in the first place
One more piece that gets glossed over. Many vehicles solve the spare problem with a compact temporary "donut" tucked under the cargo floor, which would have ended this entire debate decades ago. Jeeps do not, and the reason is the driveline.
Four-wheel-drive systems assume all four tires are rolling at nearly the same rate. Put a significantly smaller spare on one corner, and the transfer case, differentials, and couplings that are meant to absorb momentary speed differences end up absorbing a permanent one. Sustained, that means heat and wear in parts that are expensive to replace. A full-size spare that matches diameter and tread is the correct answer for a 4x4, and it is also why anyone who upsizes to 35s needs a fifth 35, not four.
A full-size 33 or 35 is too big to hide under the floor of a short-wheelbase open-body 4x4. So it goes on the back. Everything else follows from that.
What it means for the back of your Jeep
Practically speaking, the rear-mounted spare hands you the single most visible flat surface on the vehicle. It is at eye level in a parking lot; it is what the truck behind you reads at every stoplight, and it is round, centered, and unbroken. No other panel on a Jeep is this easy to see or personalize.
That is why tire covers and tailgate decals have been a thing for as long as Jeeps have had spares hanging off the back. At Jeep Decal Store, we cut our vinyl decals in-house in South Carolina from ORACAL 651, a calendered intermediate film, so a tailgate or quarter-panel graphic lays flat and stays put. Our spare tire covers are a different animal entirely: they are printed to order on a polyester-nylon weave, not vinyl, which is what lets a full-wrap design hold color across a curved surface.
If you are sizing one, get the tire size off the sidewall first, because a 33 and a 35 are not interchangeable, and check whether your Jeep needs a camera port. Our guide to spare tire covers walks through materials, sizing, and fit in detail. When you know what you need, the tire cover collection is where to look, and US orders over $59 ship free.
FAQ
Why is the spare tire on the back of a Jeep?
Because there is nowhere else to put a full-size spare on a short-wheelbase, flat-floored, open-body 4x4. The original 1941 Willys MB had a solid rear panel and no cargo well, so the spare went on the outside. Every Wrangler since has kept it there for the same packaging reasons, plus because a 4WD driveline needs a full-size matching spare rather than a compact donut.
Did the original World War II Jeep have the spare on the tailgate?
No, because it did not have a tailgate. The Willys MB and Ford GPW had a solid rear tub, and the spare bolted to the flat rear panel through a dedicated carrier bracket. The tailgate came later, first appearing experimentally on the CJ-1 prototype in March 1944 and reaching production on the civilian CJ-2A in 1945.
Where was the spare on a CJ?
On the body, on the passenger side, once the tailgate took over the rear panel. On early CJ-2As, it sat ahead of the rear wheel and on later ones, behind it. That side mount was the civilian Jeep signature from 1945 into the 1980s.
When did the spare move back to the tailgate?
The military got there first. The Willys M38, built from 1949 to 1952, mounted its spare high on the passenger side of the tailgate, and the tailgate stamping was revised on 4 May 1951 with four cutouts to clear that carrier. On the civilian side, the spare was on the gate by the time the Wrangler YJ arrived in 1987, and it has stayed there through the TJ, JK, and JL.
Why does the Jeep Gladiator carry its spare under the bed instead?
Because it finally had room. Jeep's launch material for the 2020 Gladiator specifies a full-size spare mounted under the bed, behind the rear axle, in a carrier rated for up to a 35-inch tire. A five-foot bed on a longer frame gives you space a Wrangler does not have, and the Gladiator's damped, power-locking truck tailgate was not designed to carry a spare.
Can the factory swing gate handle a 35-inch spare?
Not without help. When Jeep introduced the Xtreme Recon package in July 2021 with factory 35-inch tires on the four-door Rubicon and Rubicon 392, swing gate reinforcement was part of the package alongside the wheels, the 1.5-inch lift, and the 4.56 axle ratio. If you are upsizing on your own, plan on a reinforced hinge or a bumper-mounted carrier.
Is the backup camera really inside the spare tire?
On the JL, the camera mounts in the center of the rear spare carrier, protected by a metal housing, and the cover also locks the tire to the carrier. Jeep chose that spot because the Wrangler always has a rear-mounted spare, so the camera wouldn't be obscured by any wheel and tire package. That is also why some tire covers need a camera port cut into them.
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