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Thursday, April 14, 2011

Phooey on Flats, Part II

This week we are looking at the problems of flat tires. You should read the first blog in this series if you haven't done so already.

There are a variety of solutions that reduce flat tire problems. We will be evaluating these using reasoning techniques taught in Excel Math. We may not come up with a single definitive solution - but of course the answer often depends on how you phrase the question.


Advantages of run-flat / self-sealing / self-supporting tires
  • Driver and passengers aren't inconvenienced by (most) tire damage.
  • A driver can continue for 100-150 miles at 50mph with a damaged run-flat tire.
  • No need for a jack or spare tire.
Disadvantages of run-flat tires
  • Weight of the tire is 10-20% higher than a regular tire
  • Price is 20-30% higher than regular tires
  • Ride and handling often inferior to normal tires
  • Tires usually can not be repaired after having a flat
  • Few dealers have equipment to change run-flats
  • Limited availability of tires in stores (only 3% of tires sold) so it may take days to get
  • Specialized wheels may mean owner is locked into one type of tire

Advantages of an inflator with sealant
  • Smaller and cheaper than a regular or mini-spare
  • Wheel doesn't need to be removed for re-inflation
Disadvantages of an inflator
  • Might not work if the sealant has been stored for a long time, or if it freezes
  • Won't help if tire or rim are badly damaged
  • Residue from inflator may ruin equipment or the tire valve or pressure sensors
  • Inflator gas may be flammable and dangerous for technicians 

Advantages of a roadside service
  • Someone else does the hard work of changing or replacing your tire
  • Convenience for the driver and passengers
Disadvantages of a roadside service
  • Cost and complexity of the system
  • Unpredictable contact (phone may not be available)
  • Wait time for the technician to arrive
  • "Big-brother is watching me" issues 

Advantages of TPMS
  • Gives advance warning of a tire "going flat"
  • Reduces the likelihood of 75% or more of flat tires
  • Reduced tire wear and increased energy efficiency from keeping tires inflated correctly
Disadvantages of TPMS
  • Additional cost to vehicle manufacturers and owners
  • Another warning light for owners to interpret
  • Inconvenience of false alarms
  • Need to replace sensor batteries
  • High potential for damage when tires are replaced
  • Unlikely to last the lifetime of the vehicle
Now that you have seen the four primary solutions to flat tires, what do you think? How would you go about selecting a solution? Tomorrow we can do a case study and try one of our elementary math problem-solving techniques.

In the meantime, enjoy the famous Michelin poster introducing Mr Bibendum, who says:

"Now We Must Drink, that is to say, 
To Your Health, Gentlemen!"
The Michelin tire swallows up the obstacles 
(road hazards, nails, glass, etc.)

Alas, a few years ago, in a frenzy of political correctness,
Michelin put him on a diet, took away his drink and cigar, 
then gave him a smile and a green plant.

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