December 4, 2001
Many U.S. Passenger Cars Are Driven
on "Bald" Tires, NHTSA Research Shows
U.S. Transportation Secretary Mineta Announces Launch Of Major Nationwide
Campaign to Promote Tire Safety
Responding to new studies showing that a significant number of American
motorists are driving on bald tires and that many gas stations that provide
air pumps fail to provide accurate tire pressure gauges, U.S. Transportation
Secretary Norman Y. Mineta today urged motorists to closely monitor their
"It is extremely important to motorists' safety that they ensure their tires
have ample tread and are properly inflated," Secretary Mineta said.
"Motorists who drive on tires that are bald or substantially under-inflated
risk injuries or fatalities."
To better protect motorists, the U.S. Department of Transportation's
National Highway Traffic Safety Administration (NHTSA) is launching a new
tire safety campaign based on the theme: "Tire Safety: Everything Rides on
It." The purpose of the campaign, to involve radio public service
announcements, print ads and brochures, is to stress the importance of
proper tire inflation and vehicle load limits. The campaign is also designed
to encourage motorists to check their tires monthly, as well as prior to a
long trip, to be sure they have adequate tread.
"It is vitally important that motorists monitor tread depth to guard against
tire failure and replace unsafe tires. Checking tires is a crucial element
in regular vehicle maintenance," said Dr. Jeffrey W. Runge, NHTSA's
According to a major survey conducted by NHTSA, fully 9 percent of passenger
cars on U.S. roadways are driven with at least one bald tire.
Moreover, another major NHTSA study found that 14 percent of gas stations
are either not equipped with air pumps or have malfunctioning pumps. Also,
only 49 percent of gas stations that are equipped with air pumps provide
tire pressure gauges, which are critical to determining if the correct
amount of air has been delivered to tires. However, for a nominal price,
motorists can purchase a tire pressure gauge.
To help vehicle owners better monitor the air pressure in their tires, NHTSA
in July proposed a new federal motor vehicle safety standard that would
require the installation of tire pressure monitoring systems in new
passenger cars and light trucks. The new system would warn the driver when a
vehicle has a significantly under-inflated tire.
One alternative would require that the driver be warned when the pressure in
one or more tires, up to a total of four tires, has fallen to 20 percent or
more below the vehicle manufacturer's recommended cold inflation pressure
for the vehicle's tires, or a minimum level of pressure to be specified in
the new standard, whichever is higher.
The other alternative would require that the driver be warned when tire
pressure in one or more tires, up to a total of three tires, has fallen to
25 percent or more below the vehicle manufacturer's recommended cold
inflation pressure for the vehicle's tires, or a minimum level of pressure
to be specified in the new standard, whichever is higher. Only one version
will be in the final rule.
Tire tread provides the gripping action and traction that prevent a vehicle
from slipping and sliding, especially when the road is wet or icy. In
general, tires are not safe and should be replaced when the tread is worn
down to 1/16th of an inch. Tires have built-in treadwear indicators that let
a motorist know when they should be replaced. These indicators are raised
sections spaced intermittently in the bottom of the tread grooves. When they
appear "even" with the outside of the tread, it's time for tire replacement.
Another method of checking tire tread involves use of a Lincoln penny. The
motorist should place the penny upside down within the tread. If the top of
Lincoln's head is visible, the tire needs to be replaced.
NHTSA's new tire safety campaign will involve three new public service
announcements to run on 2,000 radio stations throughout the country; print
ads in newspapers and magazines; and more than 500,000 flyers to be given
free-of-charge to consumers through tire retail outlets and other channels.
Some of the materials will be in Spanish as well as English. Consumers can
obtain tire safety information from NHTSA by calling the agency's Hotline:
888-327-4236. NHTSA's new flyer and brochure, both titled "Tire Safety:
Everything Rides on It," can be viewed on the agency's web site,
Printed materials used as part of the campaign will be distributed by NHTSA
as well as Championship Auto Racing Teams, Inc. (CART), the Rubber
Manufacturers Association (RMA), and the Tire Association of North America (TANA).
NHTSA's analysis of tire wear was based on information gathered on 6,240
passenger cars during a 14-day period earlier this year. Information for the
survey was collected with the cooperation of motorists who visited gas
stations for refueling at 300 sites in urban, suburban and rural settings
located throughout the country.
To conduct its survey on air pumps at gas stations, NHTSA collected
information at the same 300 stations where data were gathered on tire wear.
Just 139 of those 300 stations were found to have working air pumps, along
with tire pressure gauges. These stations were later revisited to evaluate
the accuracy of their gauges.
Key findings of the NHTSA study on tire tread include these estimates:
Nine percent of passenger cars are being driven on at least one "bald" tire.
(For purposes of this survey, a tire was considered bald if it had 1/16th of
an inch or less of tread depth.) Bald tires are between 1.5 and 1.8 times
more likely to be underinflated than are tires with deeper tread, depending
on tire location. Key findings of the NHTSA study on gas station air pumps
include these estimates:
Well over 90 percent of U.S. gas stations are equipped with air pumps.
However, nearly 10 percent of these pumps are out-of-order. Fewer than half
of the pump-equipped gas stations also provide a tire pressure gauge for
customer use. Nearly 20 percent of the stations providing customers with
tire pressure gauges on their air pumps use gauges that over-report the
pressure present in a tire by at least 4 psi (pounds per square inch) or
more. (This means that motorists who use such gauges in the belief that they
are inflating their tires to the recommended pressure would, in fact, be
under-inflating them by 4 psi or more.) At the pressure levels that are
typical for most passenger cars or SUVs, nearly 10 percent of gas station
air pump gauges over-report by 6 psi or more.
A NHTSA research survey of U.S. passenger vehicles that was released in
August found that 27 percent of passenger cars on U.S. roadways are driven
with one or more substantially under-inflated tires. In addition, the survey
found that 33 percent of light trucks (including sport utility vehicles,
vans and pickup trucks) are driven with one or more substantially
A radial tire can lose much of its air pressure and still appear to be fully
inflated. Operating a vehicle with substantially under-inflated tires can
result in a tire failure, such as instances of tire separation and blowouts,
with the potential for a loss of control of the vehicle. Under-inflated
tires also shorten tire life and increase fuel consumption.
Tires should be inflated in accord with the vehicle manufacturer's
recommendations. These can be found in the owner's manual or on a placard,
which is often located in the glove compartment or on the driver's doorjamb.
Motorists should not rely on visual tire inspections to determine whether a
tire is properly inflated but should use a tire pressure gauge to do so.
Like tires that are under-inflated, bald tires also pose risks to motorists.
A tire with insufficient tread can cause a driver to lose traction,
especially under wet conditions. In addition, bald tires are more prone to
damage caused by road debris.
NHTSA's National Center for Statistics and Analysis conducted the two new
studies. Statistics from the studies are contained in research notes on the
agency's Website at: www.nhtsa.dot.gov/people/ncsa.