Piston Slap: “Spare” Me from Dry Rot!

TTAC sastexan commentator writing :

With the extreme cold in the US and seeing some shredded tires on the highway this week (I actually had a flat tire myself, not sure what caused it but maybe last week I was on the FR- S in a parking lot with lots of broken ice around the edges), I got thinking about spare tires.

Many of the best and brightest have “guardian” cars, including myself with our old Camry. Tires have a limited lifespan due to dry rot and I guess spare tires fall into this category. The Camry’s spare tire is the original 14-year-old tire (at least the full-size spare tire). How often do people change their parts, if ever? Has anyone with an aged spare pulled it out of dry rot? Can you just order a new space-saving replacement part off the tire rack?

Takes care,


Sajeev replies:

Very interesting question, which raises even more questions! Please note these things before proceeding:

  • Tires dry out and rot more slowly when they live indoors without exposure to sunlight (UV rays).
  • You may not see visible cracks like other rotten tires, but rest assured, at some point, the rubber has petrified like a rock.
  • The chances of getting caught by a rotten temporary spare tire are less likely than with a regular tire, because no one wants to ride around in that little donut for an extended period of time.
  • Low air pressure may be the reason for a spare blow, as they tend to leak profusely after a few years of hibernation in a trunk.
  • The items listed above will not necessarily apply to externally mounted truck/SUV/CUV replacement parts. Treat them more like your other four-wheelers.

Outboard Mount Full Size Aftermarket Owners: change the tire every 5-10 years… more or less, depending on your tolerance for risk and your driving needs. Â Or reuse one of your “old” tires as a spare when you upgrade to new tires for your regular wheels. And if you’re lucky enough to have a matching fifth wheel as a spare (or the bad luck of having 5 steel wheels on your ride) just swirl it in the mix.

Owners of temporary externally mounted spares? AN Good question as this is a future dilemma for my little Ranger pickup. On the other hand, this could look like our next case…

In-house spare parts owners? Who knows the safe lifespan, but I’ll bet 10+ years is fine, as I used the original part from my Mark VIII for short hauls in urban conditions. I’d change my tune if I were driving hundreds of miles a day on country roads…grabbing spare tires from Taurii and Helicopter Fusions in the process.

Whenever you’re looking for new rubber, well, yes, Tire Rack sells parts… but I guess the best unbranded donuts from China are traded in for less money from another supplier, like what happened when my 1983 Ford Sierra needed new tires on it space saver by unobtanium size for a measly $34 each. Which is more than enough for the job.

In the case of your Camry? I say replace it (full size spare in trunk) with one of the outer tires when it’s time to change shoes. Or pick up a used tire at any local store for $20. Â Or just make sure it’s inflated to spec and you’re driving SLOWLY (ie 50 mph or less) for a short period of time. There is no wrong answer here, unless you are stuck in the middle of nowhere and have to rely on a new tire to get hundreds of miles in inclement weather.

Like everything in life, this Piston Slap comes down to: It depends.

So watch the tire and keep it inflated to spec. It’s a good start. It’s up to you, the best and the brightest.

Send your questions to [email protected]com. Don’t skimp on the details and ask for a quick resolution if you’re in a hurry…but be realistic and use your make/model specific forums instead of TTAC for more timely advice.

[Image: Shutterstock user Wachira W.]

Source : thetruthaboutcars.com

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