## Wednesday, April 13, 2011

### Phooey on Flats, Part I

For the next few days I will focus on flat tires (on your car, not your bicycle).

You might ask, How can elementary math be helpful with a flat tire? Fair enough; here are some processes that Excel Math covers as we help kids learn "math". They can be used when considering flat tires.
• Reasoning using logic
• Reasoning using patterns
• Reasoning by trial and error
• Reasoning using a possibility chart
• Reasoning by process of elimination
• Solving problems using deductive reasoning
• Estimating which answer is most reasonable
• Reasoning by examining evidence and making notes
• Reasoning by working backwards from a given solution
• Determining if there is enough information to solve a problem
[Speaking of observation, did you notice I arranged these concepts in order of length rather than any other logical sequence?]

Am I just assuming that reducing flat tires is a valid subject for logical problem-solving? Do you need data to convince you a flat tire may be a clear and present danger?

How many flat tires occur every year?
• US - 220 million flats per year; about one flat per passenger car per year.
• US - 23,000 vehicles are damaged due to blow-outs, to the point they must be towed.
• US - 1.2% of traffic fatalities are due to tire-related accidents.
• US - tire blow-outs are most frequent on light trucks in southern states during hot months.
• UK - One flat tire (tyre) per 20-25,000 miles traveled.
• UK - 30-40% of drivers had a flat in the last year.
• UK - flats comprise 10% of total vehicle breakdowns.
• EU - flat tires account for 28% of breakdowns of 112,000 commercial vehicles in 2010.
• On average, a driver will have 5 flat tires in their driving lifetime.
What types of flats might occur?
• 25% are blow-outs; sudden loss of pressure with dramatic damage to the tire.
• 25% slow leaks that happen when driving; often result in a ruined tire from driving on it.
• 50% discovered when the car is parked; inconvenient but not normally ruinous.
Problems related to flat tires:
• It is dangerous to stop to change a tire on a freeway and/or at night.
• It can be difficult and dangerous to raise the car with a jack.
• Wheel nuts can be too tight to remove.
• Alloy wheels can stick to steel hubs making it difficult to remove the wheel.
• It can be hard to line up the wheel and the hub when replacing the wheel.
• If you have a spare it's usually under the stuff in your trunk.
• The dirty flat tire has to be lifted and stored in the trunk.
• If you get another flat before your tire is repaired you will be stranded.
• They always happen at an inconvenient time.
That should be enough to get us started. Tomorrow we will look at possible solutions.

1. Where did you get your data?

1. Thanks for contacting us at Excel Math.

The Flat Tire blog contained original research, and because it was 12 months ago, it's hard to reconstruct without doing all the work again.

If this is the data you are referring to:
US - 220 million flats per year; about one flat per passenger car per year.
US - 23,000 vehicles are damaged due to blow-outs, to the point they must be towed.
US - 1.2% of traffic fatalities are due to tire-related accidents.
US - tire blow-outs are most frequent on light trucks in southern states during hot months.
UK - One flat tire (tyre) per 20-25,000 miles traveled.
UK - 30-40% of drivers had a flat in the last year.
UK - flats comprise 10% of total vehicle breakdowns.
EU - flat tires account for 28% of breakdowns of 112,000 commercial vehicles in 2010.
On average, a driver will have 5 flat tires in their driving lifetime.
25% are blow-outs; sudden loss of pressure with dramatic damage to the tire.
25% slow leaks that happen when driving; often result in a ruined tire from driving on it.
50% discovered when the car is parked; inconvenient but not normally ruinous.
then I can tell you that it was constructed from many different sets of source material:

a. some from a US agency called NHTSA (when issuing their TPMS requirement),

http://www.nhtsa.gov/cars/rules/rulings/tirepresfinal/safetypr.html
and
http://www.nhtsa.gov/cars/rules/rulings/TirePresFinal/FEA/TPMS4.html

b. data the tire manufacturers themselves (usually when pitching run-flat tires),
c. data from a large tire company our editor worked for -- before Excel Math,
d. data from the auto clubs (AAA in US, AA and RAC in UK, ADAC in Germany, etc.).
e. Wikipedia's page on flat tires

http://en.wikipedia.org/wiki/Flat_tire

Sorry it's not easier to source, but this is a set of numbers that no one cares about enough to construct on a regular basis.
For example, the "5 flats per lifetime" is based on total flats per year, total miles driven per year, total drivers and years of driving, etc and extrapolated from that data.

Some of us who work on cars have changed way more than our share of flat tires - maybe 15-20. We don't drive very far, but have older cars, drive on bad roads, and drop the occasional sheet metal screw in our driveways… :-(

Thanks

Managing Editor, Excel Math