Police Tech & Gear
with Tim Dees
Departures from traditional tire design
You may never need to put air in your tires again
Most of us don’t pay a lot of attention to our tires unless they go flat or blow out. Now that most new vehicles have low pressure sensors that display a light when one or more tires needs air, even fewer people check their tire pressure regularly.
Some new technology may eliminate the need to check it ever, or to put more air in from time to time.
Goodyear is doing research to produce tires that maintain their own optimum air pressure level. Called Air Maintenance Technology, the tire employs an internal sensor and a pump mechanism that runs around the circumference of the tire, underneath the tread.
When the sensor detects that the internal pressure has fallen below the preset limit, a valve opens to allow air from outside the tire to be drawn into a pumping tube. The air is compressed by the rolling motion and deformation of the tire and released into the tire interior.
The entire mechanism is contained within the tire, so there is no need for any connection to the vehicle’s electronics.
Where the Rubber Meets the Road
The technology was rolled out at an international commercial vehicle show in Germany in September. There is still no product for sale that incorporates the mechanism. When it does become available, it will be marketed primarily to commercial vehicle owners.
The American Trucking Association says that half of all on-the-road breakdowns involve the tires of the tractor or trailer, and that tires are the single largest maintenance cost for commercial fleet operators.
Underinflated tires aren’t just more prone to break down. Goodyear’s estimates are that a 10 percent drop in tire pressure results in a one percent loss in gas mileage. Tires that are underinflated by 10 percent also experience a drop in tread life between nine and 16 percent.
When I was an editor in another life, EVOC instructor Sgt. Dave Storton of the San Jose Police Department produced an excellent article for me on the importance of having optimal pressure in your patrol car’s tires. It’s no longer available on that website, but it is reproduced here.
This is the sort of information that could stand repeating during roll call training.
Another approach to avoiding tire pressure problems is to do away with the inflated torus (for folks not up on your topological nomenclature, that’s the shape otherwise called a “donut”) model, replacing it with a flexible framework between the tread and the wheel.
We wrote about these last year, but they haven’t been available for any high-speed applications.
Britek Tire and Rubber has patented a bicycle tire design based on this principle and is trying to find a manufacturer to help them market it. Their brainchild is called the Energy Return Wheel (ERW), and uses elastic cushions, similar to spokes, between the tread and wheel. Britek claims that energy from bumps against road obstacles is converted into forward momentum, instead of to the rider and frame.
I’m not enough of a physicist to say whether this is possible, but it’s an interesting idea.
The cushions of the ERW are adjustable, so the rider can get a softer or harder ride, as they prefer. Britek has a video available on their website that shows the tires in use on a mountain bike. Whether this can be extended to a road bike or motor vehicle model remains to be seen.
Previous internal frame tires have had trouble with durability at high speeds. Having your tires disintegrate during a vehicle pursuit can ruin your day.
Until these technologies become available — if they ever do — make it part of your vehicle check-out procedure to verify the tires on your car are inflated to spec.
As Storton’s article referenced above explains much better than I can, proper tire inflation contributes heavily to the handling characteristics and safety of your car. We’re still losing about half the cops killed in any given year to vehicle incidents.
Take every precaution to ensure your car is as serviceable and dependable as you can make it.