Excel Math: 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.

1. RUN-FLAT TIRES

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

2. TIRE INFLATORS

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

3. ROADSIDE SERVICE

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

4. TIRE PRESSURE MONITORING SYSTEMS

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!"