Here is something I’ve been toying with on and off over the years. Might be the answer to a question nobody has asked.

For those that don’t see the value of a functional spare tire, move along. You either don’t drive your car much, or never venture to areas where roadside assistance and cell phone service is sparse. Or you just like living dangerously. That’s cool. That’s your choice. I’m not looking to debate that point here. If on the other hand, you do prefer to have a good spare in the trunk like I do, read on. You might find this interesting.

One of the challenges I’ve run into after installing aftermarket tires and wheels on my Mopars is having a spare tire that closely matches the rear diameters. This is critical if you have a sure grip differential and don’t want to wear out the clutches in short order.

Just mounting the same size tire as the rears on a spare wheel doesn’t work. Many of the popular sizes won’t fit in the trunk, or function as a front tire. Truck space is at a premium in E-bodies, so even if they do fit, you’re left with very little space for anything else. They also can be really freaking heavy, weighing about 60 lbs in some cases.
Another potential issue is brake clearance if you are running larger than stock brakes.

Two of the most popular rear tire sizes are 255-60-15 and 275-60-15 with diameters of 27 and 28 inches respectively. Those are relatively tall tires, and their widths make it impossible for them to fit under the package tray in the trunk storage location.

So the challenge is finding a narrower tire with a similar diameter. There really isn’t much out there. Some 70 series tires come close, but the cost of a new tire and hassle of cleaning up a crusty wheel got me looking for other options. That led me to start looking at late model compact/temporary use spares.

While most “donuts” are way too scrawny, a lot of SUVs are now coming equipped with a 155-90-16 as a spare. These measure out just shy of 27 inches in diameter. Perfect relative to the 255, and probably as close as you’re going to get to the 275.

The bigger challenge is finding a wheel for it. All of the tires I’ve found in this size come on a wheel with a ton of positive offset which just won’t work. Jeep Cherokees are a good source for the tire (note that some have a 125-90-16), and have the correct bolt pattern, but the wheel has about 3 inches of offset and it contacts the brake drum preventing the wheel from seating on the drum face in some cases. I’ve actually used one of these spares with wheel spacers, but it’s not a very elegant solution.

Searching for another 16-inch spare with the correct bolt pattern and less offset I found the spares used in Ford Crown Vic, Mercury Marquis and Lincoln Town Car. The later model years of these come with a 16x4 steel or 16x4.5 aluminum spare. These appear to have less than an inch of offset. Tire size is scrawny at 145-80-16 (25 inches), but it’s the wheel I’m after. The Town Car is your source for the aluminum, which is what I chose to test.

Anyone who as ever tried to install an OEM Ford wheel on a Mopar knows that the center register is too small in most cases. These spares are no exception. A few minutes with a die grinder takes care of the issue though. Only a couple thousandths need be removed, so I took my time and test fitted frequently.

After getting the wheel to bolt up, I made a trip to my local used tire store with both the Lincoln TC spare and Jeep Cherokee spare. For $10, I had the tire from the latter mounted to the wheel of the former.

What it yields is a compact spare perfect for a Sure Grip equipped Mopar. The aluminum wheel looks pretty trick. The whole thing weighs under 40 lbs, which is a modest ten pound savings over at typical conventional spare. I definitely wish I would have had one of these for the space savings in the trunk of my Challenger on the Power Tour a couple years ago. I’d like to have tested it over the 13 inch Cobra brakes on the Cuda I use to have.

While this spare might a solution to a number of problems, there is one it won’t solve. If your 275-60-15 goes flat, after you install your spare, you still have to figure out where to carry that flat tire. It’s not going to fit in your spare tire storage location.

I’ve probably got $70 invested in this exercise. Both the wheels came off Ebay, but a trip to the local salvage yard may have yielded both for less than what I paid.
The Ford “Panther” series cars are the only ones I’ve found with the needed wheel size, offset and bolt pattern. I think there maybe some obscure Mustang or Thunderbird spares as well.

There are a lot more sources for the tires: Jeep Cherokee’s, Honda Pilots, GM S-series pick-ups, and some GM SUVs. I’m sure there are others. Small to midsize SUVs seem to be the best source.

Posted are some pictures showing the examples and results. Standard disclaimers apply. This has only been tested on my 72 Road Runner with factory discs and drums.