Spare Tire kit for Chevy Volt


I recently purchased a 2019 Chevy Volt, which feels like a futuristic spaceship compared to the trusty old Prius I’d been driving for the past 13 years.  The Volt has been great thus far, and after 600 miles is delivering well over 250 mpg.  I have no idea what the actual mpg is, since the gauge only goes up to 250, and it pegged out two weeks ago.  I love the quiet torque of the electric motor, and having 9 gallons of gas in the tank in case I need to drive more than fifty or sixty miles — but what I really love is burning very little gas at all.  In those six hundred miles, the gas gauge hasn’t budged.

There’s just one  downside.  For reasons best known to the bean-counters at General Motors (and other car manufacturers, unfortunately), spare tires have been disappearing from the trunks and hatchbacks of sedans over the past few years.  Full size spares were long ago supplanted by small donut spares, but even those are beginning to vanish, replaced by a glorified can of Fix-a-Flat and a small electric air pump.

This is certainly more convenient than hauling out a jack, chocking the wheels, elevating the car, struggling to loosen the lug nuts, muscling the flat tire off, muscling the spare tire on, then tightening those lug nuts in the proper order, lowering the car, stowing the flat tire and jack in the back and — finally — continuing on your journey.  Of course, fifty bucks a year will buy a Triple A card to summon a sturdy fellow who will cheerfully do the dirty work required to get you rolling again while your hands and clothes stay clean.  Not a bad option to have in your back pocket.

From what I’ve read, the OEM goop-in-a-can that comes with the Volt works fine for small, clean nail punctures, but I’ve seen reports that the sealant goo can ruin the pressure sensor inside the tire, which will then have to be replaced. I don’t know what GM charges for one of those sensors, but none of their parts are cheap. As usual, convenience comes at a cost — and if you happen to nick a curb a little too hard or suffer a major blowout that tears the tire, an entire truckload of Fix-a-Flat won’t help you.  The low-rolling resistance tires that come on hybrids, plug-in hybrids, and pure electric cars to increase mileage have weak sidewalls, rendering them particularly vulnerable to damage.  Whatever the cause, should your Volt suffer such serious tire damage, it will have to be towed on a flatbed truck to the nearest dealer or tire shop, where you’ll wait at the back of the line to have that tire replaced… and if this happens at night or a Sunday, you’re shit out of luck.

This doesn’t seem bother many Volt owners who apparently believe that Bad Things only happen to Other People — and hey, maybe they’re right… or maybe I’m one of those Bad People, because I’ve learned the hard way to follow a “hope for the best but expect the worst” approach to life.  Having felt the stinging backhand of fate whenever I was foolish enough to let my guard down, I’m not about not trust a little can of carbonated goo to get me back on the road when I get a flat.  And I say “when” rather than “if” for a reason: eight days after taking delivery of my new Volt, I found a sheet metal screw imbedded in the tread of the passenger side rear tire. The leak was slow enough that I could get to the local garage which plugged the hole, but this is why  any car I own will be equipped with a spare, one way or another.

Chevy offers a spare tire kit for the Volt for between $340 and $550.  I might have been willing to spend $340, but $550 — the price quoted by the parts department of my dealership  — seemed a bit steep. Besides, they didn’t have any spare kits in stock, and added that they’d been on back-order “for quite a while now.”

Still, if you’re blessed with a fat bank account and don’t mind waiting, the Chevy kit  would be the simplest way to go, but being unwilling to drive my car for God knows how long before my dealership finally had a kit in stock to sell me,  I decided to go the DIY route.  A consultation with the Oracle of Google came up with this, which was very helpful.  After considerable contemplation (and checking out another solution to the spare problem), I decided to borrow a little from each approach, since neither fully met my needs.

You might want to take a look at both those links before you proceed — one of them may be perfect for you — but here’s the path I took.

My first task was to get a donut spare that would fit my Volt, which I found on E-Bay, complete with a jack and tire iron, for $160 delivered.  According to all the information I could find, the proper size donut spare for a Generation Two Volt is a T115/70R16/92M, but a close look at mine revealed that it was actually a T125/70D16/96M.  A call to a tire store revealed that my spare was “a little bit taller and a little bit wider” than the right tire.  The Oracle of Google confirmed that the difference was slight — about a half inch larger diameter and a not quite a half inch wider than the OEM donut spare.  The wheel well appeared plenty large enough to accommodate my  spare, but there was only one way to find out — bolt it on and see what happened.

The jack that came with the spare was a sad, spindly little piece of crap I wouldn’t trust  to lift much more than a loaf of bread, but I tried it anyway. Sure enough, the rear wheel wasn’t even off the ground before that jack began leaning to one side like the famous Tower of Pisa, so I got my 3000 pound capacity scissor jack from the basement, which levitated the car with ease.

Scissor Jack

Off came the tire and on went the spare, after which I took a six mile drive that was smooth as silk — no problems at all.  The tire fit fine, and as bonus, has a 15% higher load rating than the OEM spare.  I’m not sure that matters, but it can’t hurt.  The only anomaly  was that the donut spare was rather warm when I pulled it off, so I  checked the air pressure (which I really should have done before going for a drive…)  and found that it only had 45 psi, a good 15 pounds below what it should be.  Remember that if you buy a spare from E-Bay or anywhere else — check the tire pressure with a quality gauge.  I pumped it up to 60 psi and was ready to secure the tire in the hatchback trunk.

Plan A

My first thought was to utilize a “Spare Tire Hold Down Kit” from Dorman (part #41068), which I got from Amazon for $12.

Mounting Kit Plan A

The second of the spare-tire solutions I’d found on Google (the Utube video) utilized parts of this kit, but if I could install a threaded screw eye in the threaded hole Chevy has thoughtfully put underneath the hatchback floor panels, then the entire Dorman kit  — threaded hook, flange, and butterfly nut  — could be used to secure the donut spare.

Mounting parts Plan A

There was just one fat, buzzing fly in this otherwise smooth ointment — although the threaded screw eye was the shortest I could find with the proper threads, it was still long enough that a large amount of material would have to be cut out from underneath the hard plastic foam panel of the hatchback to allow the screw eye and hook to fit.  The more I thought about that, the less I wanted to do it, so it was time for…

Plan B

Eventually it hit me that all I really needed was a threaded rod (to go in the same hole I’d planned to use for the screw-eye), a washer and nut to make sure that rod doesn’t come loose, and a butterfly nut to use with the flange from the Dorman kit to hold the spare tire down.  I already had the the right sized washer and nut from the screw eye, so I ordered the threaded rod and butterfly nut online from McMaster Carr: one M8x1.25 metric threaded rod, Class 8.8 steel, zinc-plated, 200mm long, along with a five-pack of Zinc plated steel M8 x1.25 mm thread, 22.23 mm base-diameter wing nuts.  I didn’t need five of those wing nuts, of course, but that was the smallest quantity McMaster Carr would sell — so now I have a few spares in case I lose one.  The parts were cheap — seven or eight bucks in all, plus a bit more for shipping.  All told, the various parts and shipping came to less than thirty dollars.

Here was my mounting kit, ready to install:

Mounting parts

First I had to access the space below the floorboards of the hatchback.  Pulling up out the cloth panel revealed this:

Stock Hatch

From left to right is a plastic pop-rivet, the OEM tire inflater kit, the 12 volt battery, and two more pop rivets.  I was able to remove the rivets by unscrewing and loosening them with a wide-blade common screwdriver, after which I popped each one off using a Number Two handy clamp to grasp the pop-rivet.  It was a bit awkward, but could probably be done using two screwdrivers, one on each side.  Once I’d unscrewed the black plastic knob atop the inflater kit, then removed it and the chromed metal piece below (which I assume is used to drag the car up on the flatbed of a tow truck when necessary), I lifted the entire black foam panel out.

Hatchback floor pre-mod

Near the center of the photo is the threaded hole in which the 200 mm threaded rod would go. I screwed the nut a couple of inches onto the threaded rod, slipped the washer on to go between the nut and the metal of the car, then gently turned the rod in as far as it would go. Using a 13 mm wrench, I tightened the hell out of that nut to make sure it stays where it is.  I think it’ll be fine, but if it ever does come loose, I’ll go back in with a lock-washer and maybe some Loctite to make sure that doesn’t happen again.

Rod in place

Now I had to think about securing my scissor jack in the slot Chevy created for it in that big black foam panel.  The smart way (as in that Utube video) would be to get a nylon strap with a retaining ring and velcro, then thread it through the slots on either side of the space where the jack goes… but I didn’t have a nylon strap, so used rope instead, with a couple of knots to keep it in place.  I’ll get a proper strap for a neater, tighter installation later.

Once the rope was threaded and knotted, I put the black foam panel back into the hatch. This was a bit tricky, since there were now two rods to go through their respective holes — one for the tire inflater kit and the new one for the donut spare — but I was patient, didn’t force anything, and it went in just fine.  I popped those three rivets back on, placing each over the white threaded rod and pushing down as far as it would go.  The scissor jack went into the slot on the right side of the black plastic panel, where I tied it down.

Jack tie-down

(No, I didn’t take a photo of the jack in place — you’ll just have to use your imagination)

The cloth panel would only go in so far with that new rod sticking up.  Using an Exacto knife, I found where the tip of the rod contacted that panel and cut a tiny “X” in the cloth, then applied a little pressure and the panel dropped down into place.  I then centered the donut spare over the threaded rod, slipped the black flange down until it contacted the interior tire rim, and screwed down the butterfly nut nice and tight.

Spare in place

My Volt is now equipped with a spare tire that shouldn’t come loose unless unless and until I suffer a truly catastrophic accident, in which case I’ll have much bigger problems than a flat tire.

One more thing: use whatever lug wrench you like, but I much prefer an X-shaped wrench like this:

Lug wrench 2

The lug nuts on a Volt are tightened to 100 foot pounds of torque, and loosening those nuts will be a lot easier with this type of lug wrench.  Just make sure it has a 19 mm socket, and you’ll be good to go. For what it’s worth, I tied mine atop the donut spare by running a rope through two of the spare’s lug-nut holes — that way, the wrench will be there if and when I need it, and won’t come loose until then.

I hope this is helpful for any fellow Volt owners who aren’t content to rely on a can of aerosol goo to get your car rolling after suffering a flat tire.  There are other ways to skin the spare-tire cat, of course — but this is the solution I came up with, and it works for me.





About hollywoodjuicer

I was a juicer in Hollywood for forty long years, and now I'm not.
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