<VV> Temp Tire Myths

Sun Sep 1 12:06:03 EDT 2019

I carried a 125/80-16 (from a Chevy S-10 pickup) temp spare in my UltraVan
for 17 years and had the opertunity to use it 4 times. The tire was rated
at 1,500 lbs and had a normal all weather tread of 4/32" (Kumho).  I did
follow the warning of no more than 50 miles with a max speed of 50 mph
except for one time.  I was in the middle of Capital Reef National Park, UT
when I had a sharp rock cut a gash in the rear tire sidewall.  I put the
spare on an limped back to Hanksville (86 miles).  We checked in to the RV
park and using the pay phone  (no cell service) ordered a new 245/45-17
tire for the rim.  Five days later UPS delivered the tire and I was able to
have the only gas station in the town to mount and air up the tire.
Jim Davis

On Sun, Sep 1, 2019 at 8:24 AM roboman91324--- via VirtualVairs <
virtualvairs at corvair.org> wrote:

> Jack,
>
> Thanks for the response.
> I agree with your position that we should always "study test results and
> make an informed decision."  That is why I asked you for a link to the
> Motor Trend article you referenced.  I am asking for the same regarding
> your Car and Driver reference.  I didn't spend a lot of time researching
> but I couldn't find either online.
> Please understand that I am not challenging your memory or knowledge but I
> also believe that we are all subject to what is known as "confirmation
> bias."  In effect, we tend to filter things we read or hear or see to
> confirm an outcome we prefer.  In the articles you reference, there might
> be words like, "During limited testing." or "Under controlled conditions."
> I don't know if that is the case but that is why I want to read about the
> parameters of the tests and the results.
>
> I will repeat my concerns from my previous post and add to them. Please
> note that these concerns are fairly obvious.
> 1. The tread depth on the mini is minuscule compared to a regular tire.
> Therefore, the tread life would be much less.  The depth of tread is barely
> at wear limit where you would be subject to an officer issuing a ticket if
> you had a standard tire.  Is this as safe as a normal tire?  This issue is
> aggravated by the smaller contact patch between the tire and the road.  A
> smaller contact patch will wear faster than a larger patch with the same
> weight, speeds, etc. in use.
> 2.  The rubber composition of the mini is harder than a standard tire.  In
> addition, the tire pressure is higher.  I believe this is because they want
> the mini to retain pressure over many years without attention.  A harder
> and stiffer tire will have poor braking and handling characteristics.  As
> in item 1 above, a tire with higher pressure and a harder substance will
> have a smaller contact patch.
> 3.  Due to both 1 and 2 above.  The already poor characteristics of the
> mini tire in normal use are far, far worse in the rain or snow.  While many
> areas of the country do not have rain and or snow year round most do have a
> rainy season as in Southern California.  I do not expect that people living
> in these areas will refrain from driving during this season or will choose
> to change their tires to go driving when the roads are wet.  Deeper treads
> and a more compliant tire are critical for safe operation under these
> conditions.
> 4.  To save weight, both the wheel rim and tire are made of much thinner
> material.  The metal rim is probably made from a less dense material though
> I am not certain of this.  This makes them much weaker if you were to hit a
> rock, pot hole or curb.  Further, with even moderate handling efforts, the
> more pronounced flexing of both metal and rubber could easily cause
> unexpected handling characteristics.  Even standard wheels are subject to
> deformation but are designed to stay as safe as is reasonably possible
> under expected conditions.
>
> 5.  The perimeter and side walls of the mini/compact tires are very thin
> with fewer plies than you would normally have in even the cheapest of
> tires. This is one reason why they are inflated to almost double that of
> standard tires.  Mini spare tires do not need to meet the government's
> standards for normal use.  This is why they are approved only, I repeat
> ONLY, for very limited and low speed use.  In fact, the government does not
> require that a spare be included with any car.  Many new cars sold today do
> not have spares of any kind as standard equipment. The only reason any are
> included is because it is traditional.  The reason compact spares are even
> minimally safe under strictly limited conditions is because manufacturers
> want to avoid lawsuits.
>
> 6.  If you have a limited slip differential, the use of a compact spare on
> one side of that axle is of great concern.  Limited slip differentials are
> designed to slip minimally when you drive around a corner.  With a smaller
> diameter wheel on one side, that differential is slipping constantly.  It
> will be destroyed in short order.  Your warranty will not cover this.  All
> wheel drive vehicles will have this problem whichever corner has the mini
> wheel.  For this reason, it is far, far more important for you to use a
> mini wheel only for a very short distance with one of these vehicles.  Of
> course, if you have a compact wheel of the same size at all four corners,
> this is not an issue.
> Regarding your aggressive driving with a compact spare, I am very happy
> that you survived the experience.  I have seen this sort of logic before.
> Here is a story to drive home my point.
> In the days of my youth, I had an acquaintance who was a degenerate drug
> abuser.  One evening, he decided to play a solitary game of Russian
> roulette.  He survived the attempt and a friend of his took the gun away
> immediately.  Using the logic that "I did something without negative
> effects." would you conclude that it is perfectly safe to play Russian
> roulette?  The fact that you have survived aggressive driving with mini
> spares doesn't mean you will continue to survive.
> I suggest that you and anyone reading our posts read each of my stated
> concerns.  Consider as to whether they are false in any way then consider
> if they lead to the same conclusion that I came to.  Put simply, the every
> day normal use of compact/mini spares on your car is tempting fate.  Sooner
> or later, their use will lead to catastrophic consequences directly
> attributable to their misuse.
> Here is "a thinker."  If compact spares are direct and safe replacements
> for regular tires, why aren't all regular tires built to the same
> specifications as the mini spares?  They are lighter and cheaper. These are
> two attributes that are very attractive to manufacturers.
> Doc~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> In a message dated 8/31/2019 1:25:18 PM Pacific Standard Time,
> socalcorvairs at yahoo.com writes:
>
> I don’t recall Motor Trend article date.Try Car and Driver’s test
> published Jan 2017.Believe what you want as a belief is just a myth, even
> from your favorite car manufacturer.Or study test results and make an
> informed decision.Many people still believe Corvairs are unsafe at any
> speed, even after testing that proved their superior handling.I have used a
> skinny spare on my Corsa in aggressive driving with no noticeable
> difference, but don’t often drive in rain or snow here in Paradise. (I live
> in California as testing proves it is the best!)Regards,Jack Pinard
> Salty but Nice!
>
>
> Jack Pinard iPhone 8s805.340.6533
>
> On Aug 31, 2019, at 10:05 AM, roboman91324 at aol.com wrote:
>
>
> Jack,
>
> Do you have a reference to a Motor Trend article?  Is the test you mention
> available online?  I couldn't find it in a quick search.
> I find it difficult to believe that the mini spares are virtually the same
> as the full size tires for the following reasons.
>
> 1. The tread depth on the mini is minuscule compared to a regular tire.
> Therefore, the tread life would be much less.  This issue is aggravated by
> the smaller contact patch between the tire and the road.  A smaller contact
> patch will wear faster than a larger patch with the same weight, speeds,
> etc. in use.
> 2.  The rubber composition of the mini is harder than a standard tire.  In
> addition, the tire pressure is higher.  I believe this is because they want
> the mini to retain pressure over many years without attention.  A harder
> and stiffer tire will have poor braking and handling characteristics.  As
> in item 1 above, a tire with higher pressure and a harder substance will
> have a smaller contact patch.
> 3.  Due to both 1 and 2 above.  The already poor characteristics of the
> mini tire in normal use are far, far worse in the rain or snow.  Deeper
> treads and a more compliant tire are critical for safe operation under
> these conditions.
> 4.  To save weight, both the wheel rim and tire are made of much thinner
> material.  The metal rim is probably made from a less dense material though
> I am not certain of this.  This makes them much weaker if you were to hit a
> rock, pot hole or curb.  Further, with even moderate handling efforts, the
> more pronounced flexing of both metal and rubber could easily cause
> unexpected handling characteristics.
> Car manufacturers offer very explicit warnings about the use of the
> spares.  They warn that they must be operated at lower speeds and for
> strictly limited duration.  This is due to the things I mention above and
> probably for additional reasons.  These tires are for temporary, emergency
> use because of their very real limitations.  The warning labels are there
> because the manufacturer knows that normal use can lead to accidents and
> law suits.
> Periodically, I have seen people on VV who contend that mini spares are
> perfectly acceptable for every day use without reduced speeds and without
> handling concerns.  I believe that anyone who uses one or more of these
> tires on a car as if it/they are the same as a regular tire is tempting
> fate.  DON'T DO IT!
> Doc~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> In a message dated 8/31/2019 7:12:16 AM Pacific Standard Time,
> virtualvairs-request at corvair.org writes:
>
>
> Message: 5Date: Fri, 30 Aug 2019 12:59:25 -0700From: John Pinard <
> socalcorvairs at yahoo.com>To: virtualvairs at corvair.orgSubject: <VV> Temp
> Tire MythsMessage-ID: <61B04664-1B06-441A-8AF0-EC404917C067 at yahoo.com>Content-Type:
> text/plain;    charset=utf-8
> Motor Trend tested many years ago and found no substantial difference in
> braking or handling at highway speeds, and tread life similar to full size
> tires.I don?t like a tire blocking access and view of enhanced engine bay,
> so temp lays flat up front only on long trips where there could be long
> wait for AAA.Found in discard pile at tire shop for five bucks.1966 Corsa
> convertible1964 Greenbrier Deluxe1965 Race Car ?97?
> Jack Pinard87 Years in No. 1 State
>
>
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