A few days ago, Ford showed the silhouette of the 2020 Ford Bronco, and the crowd went wild, in part, because of what looks like a rear-mounted spare. It’s exciting news in an era when most automakers have their spare-tire placement all wrong. The rear door is indeed where the thing belongs.
I feel very strongly about this claim, especially when talking about SUVs, because the vehicle on which I first learned to drive was a first-generation “ZJ” Jeep Grand Cherokee, which had its spare in the rear cargo area, standing upright on the driver’s side. This, as many journalists who drove the vehicle after it debut mentioned, is a waste of storage space and is thus, rather dumb.
Not to mention, it limits how big of a spare can fit back there. Just look at Matt from YouTube channel BleepinJeep resorting to leaning the second row seat of his XJ (which has the same setup) up a few degrees just to fit a 31-incher:
But Jeep “fixed” this problem on the Grand Cherokee by moving the spare tire below false-floor in the cargo area on the subsequent “WJ” generation. “Doesn’t that just sacrifice cargo area in the up-down direction?” you might think to yourself. Yes, it does. And in the case of the Grand Cherokee, it actually makes things worse, because to keep the floor at approximately the same height as the rear door opening, the fuel tank of this off-road vehicle has to sit down low in a vulnerable spot:
Some off-road enthusiasts have even resorted to cutting the spare tire-well out of the rear floor so they can move the gas tank higher, away from the treacherous terrain.
That spare tire-well, like the “in-cargo area” method that the ZJ employed, limits how big the WJ’s spare can be. So if you want to bolt 35's onto your WJ’s axles, you can forget about putting a full-size backup in the stock location. Not to mention, just to get to the tire, you’ll have to remove pretty much everything from the back of the vehicle.
It’s worth mentioning that modern automobiles tend to have their fuel tanks in front of the rear axle (and mounted fairly low), so putting a spare back there may not cause quite as many ground clearance issues as the WJ has, though the cargo area sacrifice and the spare tire size limit remain.
Another place we tend to see spare tires is under the rear of the vehicle (like under the 4Runner in the video above). This is also a poor design. Again, if I’m going to give up that ground clearance, I’d rather have a more voluminous cargo area than a spare tire there, and again, we’re limited in how big that spare can be based on the packaging space.
What’s worse is that, if I do some heavy off-roading, I can damage the wheel and the tire. And if I go mudding and get a flat, I then get to crawl underneath my vehicle and extract a filthy tire. This is less than optimal, and I haven’t even mentioned the wonkiness of the lowering-mechanisms automakers use to help owners slowly and safely gain access to that underbody-mounted tire.
Packaging the tire on the back door is simply the best solution. It doesn’t eat into cargo space, it doesn’t compromise ground clearance or departure angle, it doesn’t limit how big the spare can be (though it may require some reinforcement of the door if you put 40s on it), it doesn’t get too filthy during off-roading, it’s easily accessible and, most importantly, it’s downright sexy.
Seriously, show me one SUV that doesn’t look better with a spare tire on the back? Hell, even the tiny Ford EcoSport looks better with a big cylinder hanging off its tail:
To be sure, there are a few downsides. For one, the tire reduces rearward visibility, and it also limits what style of rear door automakers can employ—a tailgate and full lift-gate are both out of the question if the tire’s mounted directly to the door. So you’re pretty much limited to some sort of swing-gate unless there’s a separate swing-out carrier (in which a tailgate or a full liftgate are possible). In any case, getting that rear door open is made harder because that large mass is in the way.
Then there’s the issue of rear impact damage. The Insurance Institute for Highway has done a number of 5 mph rear crash tests, and found that vehicles with rear-mounted spares tend to sustain more damage.
Just take a look at this crash test of a 2000 Isuzu Trooper running into a pole at 5 mph:
IIHS’s president at the time of the study, Brian O’Neil, said the Trooper was “a very poor performer...the worst midsize SUV [the institute has] ever tested.” The organization’s report described just how much damage the vehicle sustained thanks to that big spare on the back:
The worst performer is the 2000 model Isuzu Trooper. It sustained more than $11,000 damage in the four crash tests, including more than $3,000 damage in the 5 mph rear-into-pole impact. Intrusion of the spare tire mounted on the back of this SUV crushed both of the rear tailgates and shattered the glass.
O’Neil went on to lay into the Trooper for its abysmal performance, with IIHS writing:
Sales brochures for the Trooper point to its “endurance” and claim it’s “tough enough to haul a 5,000 pound trailer.” O’Neill counters that the Trooper “isn’t tough enough to withstand a simple impact at little more than walking speed without thousands of dollars worth of damage. It’s tough enough to tow a heavy trailer, but don’t bump this vehicle into anything in reverse because it’s so fragile.”
By comparison, here’s a look at an Isuzu Rodeo undergoing the same crash test:
IIHS said in its report from 2000 that the 1996 Rodeo it had previously tested had a rear-mounted spare tire setup just like the Trooper, but that the new model’s underbody-mounted spare reduced repair costs markedly:
But the 2000 model Rodeo comes with the spare tire located underneath the vehicle (tailgate-mount optional), and damage was reduced from more than $2,000 in each rear crash test of the 1996 model to less than $1,000 for the 2000 model.
So yes, there are a few downsides to the rear mounted spare, but they’re worth the advantages,
One more thing I want to look at is the side-mounted spare, as it’s my personal favorite. Take a look at the setup on this Jeep CJ-6:
This design doesn’t sacrifice any rearward visibility, it doesn’t make accessing the cargo area any more difficult, and in a rear collision—since the tread is facing rearward—the tire might absorb some energy. Or, if the spare were mounted a little closer to the front, this wouldn’t be an issue at all. And it just looks sweet on this old Jeep.
But on a modern car, this would probably look pretty awful, and if you had anything wider than those thin nondirectional tires those old Jeeps used to wear, you’d have to be careful in tight city traffic. So really, the side-mount isn’t exactly optimal for modern SUVs.
Which is why I’m sticking with the rear-mounted tire as the best option, despite the rear crash penalty, the visibility sacrifice, and the slight annoyance of having to move it out of the way to get to the cargo. I think the benefits to cargo space, spare tire access, spare tire size accommodation, and just sheer sexiness makes it a clear winner, and I’m expecting all automakers to agree with me. Bring back the rear door-mounted spare; trust me, it’s what the world needs.