Should spare tires be placed in the engine bay again?

Spare tires and engine bays once played nicely together. Could they do so again? Upon seeing the engine bay of the Ford Bronco Sport, our awesome commenter outback_ute made an interesting comment, as it is after all what awesome commenters do:

Looks like there is enough empty space under the hood to have a frunk. Maybe store the spare there lol

This got me thinking – could we once again perhaps see spare tires mounted in the engine bay?

With each new model, our cars get bigger. But it has been the modern trend to downsize engines. Those downsized engines require less space. Further, more conventional vehicles are going in the hybrid or mild-hybrid direction. This requires automakers to find room for batteries. A typical rear spare tire well would work great for a good size battery. Since batteries are heavy, and compact spare tires are light, to have the battery on the opposite side of the engine also allows it to produce sufficient chassis balance.

The downside is that vehicle wheel diameters seem to be getting bigger and bigger, too. There were plenty of cars with small engines and spare tires mounted under the hood decades back but those wheels, even full-size ones, were much smaller than today’s wheels. Aside from that, why couldn’t an automaker attempt to fit a compact space tire in the engine bay of a three-cylinder three-row SUV?

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23 responses to “Should spare tires be placed in the engine bay again?”

  1. mdharrell Avatar

    One medium-term project for my Volvo 66 GL is to undo the previous owner’s carburetor conversion by reinstalling the original Solex side-draft so there’s room to return the spare to its proper location next to the engine. The current downdraft carb sticks up too high for this, so now the spare takes up valuable space in the trunk. The engine compartment is the same as on this DAF:

  2. Zentropy Avatar

    Turbos and associated plumbing often take up as much room as they save in displacement, and increase under-hood temperatures by 100-150F, causing tire tread to ultimately harden and crack, while softening in inner layers and potentially delaminating the tire. It’s just not a good environment in which to store a spare.

    1. 0A5599 Avatar

      I came to post that and am happy you saved me the hassle. The other thing to add is that uncluttered engine compartments are a very good thing when performing DIY maintenance or paying someone else an hourly rate to do it for you.

      1. outback_ute Avatar

        Possible but not feasible

      2. outback_ute Avatar

        Possible but not feasible

    2. Vairship Avatar

      Add the reduced temperature control brought on by having an air-cooled engine, and:

      They even put a dimple in the turbo housing to give just enough space for the tire:

      1. Zentropy Avatar

        Yeah, pretty feasible in that case. Corvairs are cool– I went on a hunt for a second-gen coupe a couple of years back, but couldn’t find a decent restorable one in my price range. I ended up going the E28 route instead.

      2. Wayne Moyer Avatar
        Wayne Moyer

        That’s the factory location but I find a lot of owners have moved them to the front.

  3. roguetoaster Avatar

    Sure, an inflator and a can of fix a flat should fit perfectly in most any engine bay.

    1. SlowJoeCrow Avatar

      From bitter experience, a can of flat fix isn’t always sufficient. After my Saturn’s second compact spare failed while sitting in the trunk I thought flat fix would do it, then I got a chunk of ceramic tile in the tire tread and the hole was too big to seal. Two cans of flat fix later I walked to the hardware store and found a plug kit, plugged the tire in the parking lot and go the third can to seal and inflate the tire. I’ve als seen valve core/stem failures that also require either a spare wheel or a tire shop to fix.

      1. roguetoaster Avatar

        Your experience mirrors that of many who have tried to use this excellent “solution” provided in so many modern automobiles in lieu of a real (trunk mounted, please) spare with tools (you can get a vehicle with tools/no spare and the other way around).

        OTOH, I only have to inflate the tires on the riding mower every other time I mow the lawn, so maybe it does have some practical application.

        1. Vairship Avatar

          In the trunk? No, then you have to empty the trunk to get to the spare. Better: under the trunk, in its own weatherproof compartment like on the Renault Dauphine and Caravelle:

          1. Sjalabais Avatar

            “Weatherproof compartment” is the cue here. My Honda had its tire mounted underneath the car, in a metallic net with some foam in the middle. It was to be lowered from inside the trunk (so you would still have to remove an eventual load), but the whole thing did, of course, rust where it sat. So I inflated the spare once in six years or so of ownership. It was just too hard to get to…

          2. Wayne Moyer Avatar
            Wayne Moyer

            The Grand Caravan has it under the car as well. Heck I think the 4Runner had it under the vehicle for awhile as well.

          3. outback_ute Avatar

            Clicked on the link, is the last photo the reason for internal emergency trunk release handles?

          4. Tiller188 Avatar

            Makes me think of my friend’s Yorkie and her tendency to stick her tongue out a little bit at rest; just sitting there happily like 😛 .

    2. Tiller188 Avatar

      While space-efficient, I have some reservations about putting a pressurized aerosol can in a hot engine bay…

      1. roguetoaster Avatar

        Not to worry, I’m sure a rupture would take care of any pesky oil leaks.

  4. Maymar Avatar

    I’m just going to put this out there now that Cadillac is getting in the EV game and I imagine Lincoln is coming. The frunk would be an excellent place for the spare (less likely to be covered in stuff when you need to get it out), and if you really want to get ostentatious, front-mounted continental kits will surely catch on.

    1. Rover 1 Avatar
      Rover 1

      An excellent idea.

    2. smalleyxb122 Avatar

      Like the front-mounted spare on a Kubelwagen!

  5. Lokki Avatar

    WHAT spare tire? BMW has decided that in the Age Of The Cell Phone my spare tire is a 1-800 number.

    A bit more seriously, run-flat tires have become such a norm for BMW that there is no well in the trunk for a spare.

    Even more seriously, with today’s 18 and 19 inch rims, anything but a Subaru boxer engine is going to have trouble finding room for even a doughnut spare in the engine bay.

  6. nanoop Avatar

    -The what tire?
    -The spare tire.
    -The spare what?
    -The spare tire.
    -The what what?