Inexpensive Spare Tire Solution!

As you all know, 355s came with a can of fix-a-flat in lieu of a spare tire. A Ferrari space-saver spare tire kit for the 355 was an expensive (about $1500) and needless-to-say, rarely purchased option. Used spares almost never come up on eBay, etc.

There are a few problems with using fix-a-flat should you get a flat tire. The sealant gums up the inside of your tire, and I've heard there may not be enough pressure in the can to inflate your tire with the weight of your car flattening it down. You can't jack your 355 up to take the weight off the flat tire, since 355s don't come with a jack.

So, here is how you may have a suitable space-saver spare, without breaking the bank:

Ferrari 355s have 18" wheels. I noticed the space-saver spare on my daily driver, a Porsche 911, was 18", so I tried it on my 355. It didn't fit. Thus I learned that there are a variety of lug-nut-hole patterns, and Porsche and Ferrari patterns are not compatible. Inspired, I asked a tire shop is any other car had an identical wheel size AND lug-nut-hole pattern to my 355. The shop had a reference book which said the Jaguar S-Type "R" was the same (perhaps others are as well, I stopped with that one option). Regular S-Types have only 16" wheels, but the supercharged "R" models have 18" wheels. Now, Jaguar S-Type "R" are not all that common, but they are more common that 355s, and every one of them has a spare tire. They were made from about 2003 to 2008. I purchased a spare tire from that model Jag on eBay, for $120. You could also try foreign car wrecker yards. Mine came with an unused Pirelli tire on the aluminum rim, which, would you believe, is Rosso corso in color.

If life were simple, the Jag wheel would just bolt on, and you'd be done. It is not quite that easy, though (speaking of life, do you know how a Ferrari is like life? Answer: it goes too fast, and you can't afford it).

To make the Jaguar spare fit your 355 you need to make two minor modifications. The center hole in the Jaguar wheel is not quite large enough to fit on the central raised flange of the 355 hub. So the center hole in the Jag wheel needs to be enlarged.

Secondly, the 355 hub has two protruding bolts (one with a rubber cover on it). On Ferrari wheels, there are holes between the lug-bolt-holes to accommodate these bolt heads. The Jag wheel has no such holes. Thus you need to drill two holes in the Jag wheel, so it will sit flush on the 355 hub.

I had a machine shop enlarge the central hole in the Jag wheel, and make two holes to accommodate the two bolts on the Ferrari hub. They charged $100 to do this. If you have suitable tools, you could probably do this yourself. If you use a machine shop, lend them one of your Ferrari wheels so they can see how big to make the center hole, and where to locate the two added holes. Note: the Ferrari wheel has holes between EVERY lug-bolt-hole, you don't need all these in the Jag wheel, only two holes (mark where they should be for the machine shop by seeing where the bolts are on your hub). Alternatively you could pull a hub off your car and lend it to the machine shop, but that is quite a bit of work.

At his point you have a space-saver wheel and tire that will fit perfectly on your 355.

You are only a few small items away from having peace-of-mind about ever getting a flat.

To mount your new spare on your car, you need new lug bolts. The Ferrari lug bolts are too long and won't tighten-up on the Jag wheel. I ordered five bolts and five washers from a hardware supplier online (boltdepot.com). The bolts you should order are hex-bolts, full-thread metric, 14 mm in diameter, 30 mm long, with a thread pitch of 1.5. The washers should be 14mm as well. I paid about $25 including shipping.

We're almost there! You need a jack. I looked online and in auto supply stores at scissors jacks (a bottle jack doesn't have enough clearance to fit under your 355). Only found heavy, bulky mostly Chinese jacks. So instead, I bought a used one on CraigsList. The seller said it was from a Mercedes, though it says "Toyota" on the top. It can easily handle the weight of one corner of my 355, and is low enough even when the tire is flat to fit under the car. I paid $10.

You need a tire-iron as well. I bought a 7/8" one at Pep Boys (local auto supply store) for $10. I like that it's a straight bar, and not a cross.

I wanted a cover for the spare tire when it is in my 355's trunk. I rather like the black cover on my Porsche's spare, and bought a similar cover from a wrecker yard. It was $25. When it arrived it was filthy (been sitting outside?) but I threw it in the clothes washer and it came out looking like new.

Voila! For about $300 you have a complete spare tire kit for your 355. Think of the peace-of-mind! It fits nicely on the floor of your trunk (I stuffed a towel on one side, so it doesn't slide around as there's an extra inch or two of room between the spare and the sides of your trunk).

Note for 348 owners: I am told your hub, etc., are the same as for a 355 so all the above should work for you as well, but I'm not familiar with 348s, so you had best confirm this yourself, or maybe someone will on this thread.

A note of thanks: I got a HUGE amount of help from Giuseppe at F&M Motorsports at 11797 W. Pico in Los Angeles (310) 445-8956. He helped with machine shop details, determining lug-bolt sizes and much more. I've used F&M for all the work on my 355, including a major belt-change service. They do truly excellent work, are fairly priced, and are wonderful people.

Below are photos showing the Jag wheel, the two extra holes added to accommodate the Ferrari hub, the jack, tire-iron, new lug-bolts and washers, and cover.
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Total weight of everything - Jaguar spare tire, jack, tire iron, lug bolts and cover is 42 lbs. I compensate for added weight by limiting 355 passenger seat occupancy to anorexic girlfriend...

 

I measured the thickness of the Jaguar spare lying flat in my 355 trunk, and it's about 6". Thus you will have that much less trunk height in your 355. I also measured the width of both the front and rear wheels on my 355, and they are about 9" and 11" respectively (either Ferrari wheel will lie flat in the 355 trunk). So worse case, where you get a rear flat, you would lose an additional 5" of trunk space over and above what is already taken by the space-saver spare. Depending on your suitcases, you might need to transfer one to your passenger footwell. Or else explain to your wife that statistically speaking, hitch-hiking is relatively safe for her at this point.
If you store a large plastic garbage bag in with the jack and tire iron, you will have something to put your (probably dirty) flat tire in, so as to keep your trunk clean.

 

A very good point. I discovered that the Ferrari lug bolts were too long after I went to mount the modified Jaguar spare wheel, so I did not ask for the Jaguar lug bolts at the time I bought my Jaguar spare. I don't know if Jaguar lug bolts have the same thread as Ferrari lug bolts. If they do, that would address this issue.

When I ordered bolts online to use as lug bolts, I would obviously have preferred bolts of hardened steel. I could find none in the relatively large 14mm size, so the bolts I purchased are not hardened.

A possible issue with using cut-down Ferrari bolts (besides the cost) is that where the lug bolts seat against the Jaguar wheel is a flat surface, not concave to receive the sloped shape of the Ferrari lug bolts. The bolts I bought have a flat shape to match the Jaguar wheel.

After installing my spare with the bolts I purchased I took a test drive, and there were no problems. I did not exceed 50 MPH (the space-saver spare has a decal warning against doing this). 14mm bolts are pretty large, there are five of them, and the idea of the space-saver spare is to simply to "limp home. " Again, I agree with you, and if I found a source of hardened bolts I would buy them.