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Fitting an Oversized Spare Tire in the Factory Location

1091 Views 18 Replies 6 Participants Last post by  Brucey

So I've had this idea rattling around in my head for a while now.

Some Volkswagen use deployable spare tires where the tire is deflated and the sidewall is reduced to near zero.

Why can't I do it? :)

I'm not actually sure how practical this is unless you have access to a vacuum pump.

I'm also not sure what effects this will have on a tire not designed for this application.

I do know that I can't find anyone actually haven done this. So I nominate myself as a guinea pig and will report anything that happens here.

But yeah. I removed the valve stem core and attached a vacuum pump on my spare tire (245/65/17 Falken Wildpeak AT3W on a Method 502) and it formed into a square/pentagon shape.

I then moved it into my spare tire well and removed the hose. In the video I had it with the wheel facing up but after letting it sit over night I confirmed I can still easily remove the tire.

I flipped the tire around so that the inside of the wheel is used for storage for my jack, tools, and air pump.

I really am surprised this seemed to have worked. I fully expected the bead to pop off.
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the old nylon belted tires would flat spot inflated on your car, in the driveway, overnight.

but I could see, maybe out of an overabundance of caution, taking the tire out every year or 2, inflating it, then deflating it and repositioning it. mark it with a piece of tape or ??? and rotate it 1/4 - 1/3 turn ???
 

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So I can see this working in theory but tires leak and holding a vacuum is very different than holding pressure. The pressure on the bead actually helps hold the pressure in a tire. Pulling a vacuum would pull the bead away from the rim. Same with the Schrader valve.
Probably bad things will happen as it expands in your tire well. At the very least you may not be able to remove it.
Then there is the stress on the tire in places it is not designed to be stressed. Imagine the strain on the internal belts.
Good luck.
 

· Brucey
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Discussion Starter · #6 ·
At the very least you may not be able to remove it.
The question is: Can the spare be extracted if the tire is allowed to return to 0psig?
I would expect yes, but with greater difficulty.
I let it sit overnight with the valve core out and was able to remove it. Certainly needed some force but less force than installing it.

I don't plan to keep it in a vacuum, it's only ran to shrink it down to fit.

In the thumbnail I actually showed the last segment filmed: The tire installed upside down and the jack and inflator kept inside of it.

Someone suggested pressurizing it in place. I think I'm going to try just for curiosity sake.
 

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It doesn't sound like getting it out is a big problem, but you could tie a piece of rope around one of the wheel spokes and run the rope around the outside of the tire to have something to pull up on for more leverage to get it out.

I would be a little worried about getting cracks in the sidewall where the tire is collapsed. It seems like just about every time I have left a car sitting on a flat the tire develops cracks where it is kind of folded over on the bottom. That may be more from the weight of the vehicle sitting on it but I would still keep an eye on that.
 

· Brucey
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Discussion Starter · #8 ·
Now that it's coming up on near a month since I did this, I was going to film a part 2 showing that it's possible to remove the tire after being in the car for some time.

I also plan to pressurize it as a curiosity.

Any other suggestions to test?

I'm not sure how to measure or quantify any condition of the tire other than putting air in it and looking for obvious cracks in the rubber.
 

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I dunno either really. Wondering if brushing a soapy water solution on the bead areas could help confirm the seal has been preserved there?
 

· Brucey
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Discussion Starter · #10 ·

I took the tire out with ease after 2 months and approximately 1500 miles. Weather varied from -10F to 70F.

I inflated it with a fancy new pump and it did hold air pressure after several hours.

I lost 0.5psi which could just be the accuracy of my cheap digital gauge I got so that viewers could read it easier than my pen style gauge.

However, I did notice a crack on the sidewall I do not recall being there before. The tire is 5 years old and has only been mounted once.

Due to the crack in the sidewall, I'm not going to recommend others do this. I will vacuum the tire back and reinstall and take my risk as a guinea pig.

I plan to buy a new spare when the current set of tires is used up so I'm not super concerned with what happens to this spare tire at this point.
 

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5 years is getting a little old for a tire that has been exposed to the elements/driven on. Due to that whole Ford Explorer issue decades back, the g'mint now frowns on use of tires 6+ years old. A new-ish tire may never get that crack....?

good report
 

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Thanks for the update.
Not too surprised an older tire would crack after being squished down like that for a while. The cold weather may have exacerbated the cracking.
Tires are generally not designed to be left flat. Exceptions are those factory inflatable spares.
btw, cracks seen on the outside of a tire seldom affect the tires ability to retain pressure. Tubeless tires have an inner liner that holds the air in. It is more flexible and not exposed to UV, ozone, etc.

A newer tire may hold up better but I think your conclusion is good...not recommended for long term.
I think I would do it to have a full-size spare for a specific trip; so that would be a couple of weeks or so.
 

· Brucey
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Discussion Starter · #13 ·
Thanks for the update.
Not too surprised an older tire would crack after being squished down like that for a while. The cold weather may have exacerbated the cracking.
Tires are generally not designed to be left flat. Exceptions are those factory inflatable spares.
btw, cracks seen on the outside of a tire seldom affect the tires ability to retain pressure. Tubeless tires have an inner liner that holds the air in. It is more flexible and not exposed to UV, ozone, etc.

A newer tire may hold up better but I think your conclusion is good...not recommended for long term.
I think I would do it to have a full-size spare for a specific trip; so that would be a couple of weeks or so.
A commenter on the accompanying video post pointed this out and I can't believe I didn't catch it originally:

That tear existed before the first vacuum. It's right at the 10 o clock position (if the Schrader valve is 12 o clock) in the very first vacuum attempt 2 months ago.

Because of this, I definitely want to test some more.

But I'm going to hesitate recommending it to anyone until someone with more authority than "some dude in his garage" can do proper tests on long term effects.
 

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· Brucey
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Discussion Starter · #17 ·
..and on AliBaba. These are all rebadged Chinese compressors.

Tangentially related:

I bought an electric bike last year for commuting. Didn't put a huge amount of thought into it.

I went online, found one with good power, good reviews, in my budget, and purchased.

With around 100 miles on it the pedal snapped off.

I messaged the seller. They said message a really strange address in China of course. I did so. No response. Sent another email. No response.

Sent another email in Mandarin (to the best of Google's abilities at least) and still no response.

Sent an email back to the seller. No response.

Left a negative review telling my story. Within 2 hours get offer from seller that they will send me a new vacuum cleaner (?) if I revise for positive review.

Tell them no I just want to have a working bicycle. End up fixing it myself.

Can't even find them on Amazon anymore. It's like they never existed.

There are many that look identical to mine however.

All with names I can't pronounce or I've never heard of. All of them seem to have glowing reviews.

But never trust reviews. :)
 

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What I've noticed over the years is that Amazon used to sell a wide variety of name-brand stuff but now it's 90% weird name chinese stuff and the brand names are disappearing.


If you're going to buy no-name weird-name stuff you might as well be buying from AliExpress - the exact same items sometimes half price with free shipping from there direct from China.
 
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· Brucey
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Discussion Starter · #19 · (Edited)
What I've noticed over the years is that Amazon used to sell a wide variety of name-brand stuff but now it's 90% weird name chinese stuff and the brand names are disappearing.


If you're going to buy no-name weird-name stuff you might as well be buying from AliExpress - the exact same items sometimes half price with free shipping from there direct from China.
It's the same strategy Jordan Belfort used.

Probably really effective.

For more comical over selling of Amazon products:

 
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