WASHINGTON -- Embattled airbag supplier Takata Corp. told U.S. regulators that 265 of its airbag inflators ruptured in the company’s testing since September.

The ruptures occurred in ballistic tests of more than 30,000 airbag inflators Takata retrieved from recalled vehicles, according to company defect reports filed with the National Highway Traffic Safety Administration on Tuesday. The vast majority of the tested inflators came from vehicles in high-humidity states lining the Gulf of Mexico and outlying U.S. territories, which have been the focal point of the Takata recalls and investigation.

Takata also disclosed to regulators that more than a dozen airbag ruptures occurred in vehicles on the road that were not covered by previous recalls. The company also cited new factors, including vehicle design, which may contribute to inflator ruptures.

The reports were filed as part of Takata’s admission to federal regulators that nearly 34 million U.S. vehicles could contain defective airbags inflators that can explode in a crash -- a defect linked to six deaths and more than 100 injuries. The acknowledgement was an about-face after the company for months refused to admit the parts were defective in the face of pressure from regulators. It is also expected to lead to the largest industrywide recall in U.S. automotive history.

As of May 1, Takata had tested 30,801 inflators retrieved from recalled vehicles, according to its four defect reports filed with NHTSA. Each report details a different “family” of inflators.

Details on testing

The reports provide the most detailed view yet of testing that Takata has done since its recall crisis emerged last year. Here’s a breakdown of figures contained in Takata’s reports to NHTSA:

180 ruptures occurred in 8,320 tests of Takata’s “PSPI-L” passenger-side airbag inflators supplied to Toyota, Honda and GM, or 2.2 percent of that inflator family tested

56 ruptures occurred in 5,911 tests of “SPI” passenger-side airbags supplied to Chrysler, Daimler Trucks, Ford, GM, Mitsubishi, Nissan, Subaru and Toyota, or 0.9 percent of that inflator family’s test population

20 ruptures occurred in 3,932 tests of passenger-side “PSPI” airbags supplied to Honda, or 0.5 percent of that inflator family tested

9 ruptures were observed in 12,464 tests of “PSDI-4” and “PSDI-4K” inflators, two of the three “PSDI” driver-side airbag inflator family variants supplied to Honda, BMW, Chrysler, Ford and Mazda. Those ruptures amounted to about 0.07 percent of those driver-side inflators tested, while 174 tests of the third driver-side derivative, called “PSDI,” experienced no ruptures.

Most of the tested inflators that ruptured came from high-humidity regions, namely coastal regions of states lining the Gulf of Mexico, Hawaii and outlying territories including Puerto Rico.

Five inflators taken from vehicles in states outside the so-called high-humidity region also ruptured. Those were from Oregon, Pennsylvania, Kentucky and two from Illinois -- though the inflators from Illinois and Kentucky were registered for years in Florida and Texas.

In the defect reports, Takata also said it knows of 84 ruptures have occurred in vehicles on the road. Of those, 65 occurred in vehicles covered by previous recalls while 15 happened in vehicles that were not recalled. Twenty-one of those field ruptures were of passenger-side inflators, while 63 were driver-side inflators.

No cause identified

Despite months of investigation, Takata, U.S. regulators and vehicle manufacturers alike have been unable to pinpoint the root cause of the inflator ruptures. Takata and others probing the defect have thus far pointed to long-term exposure to high humidity and temperature swings as leading factors behind the ruptures. They can degrade the inflator propellant over time, making it more volatile and prone to explode with too much force when activated in a crash.

In its reports, Takata estimated that its defective inflators in the field are between 8 and 11.5 years old on average, depending on the inflator family.

Also, Takata for the first time cited vehicle design as a factor that may contribute factor to a rupture.

In addition to several years of exposure to muggy climates, “Takata’s test results and investigation indicate that this potential for rupturing may also depend on other factors, including vehicle design factors and manufacturing variability,” it said in its defect report covering the 7.7 million SPI passenger-side inflators supplied to Chrysler, Daimler Trucks, Ford, General Motors, Mitsubishi, Nissan, Subaru and Toyota.

In another defect report covering 5.2 million “PSPI-L” passenger-side inflators supplied to Honda, Toyota and GM, Takata said potential ruptures are more likely to occur in some models than others even when the inflators are the same.

“Tataka’s test results indicate that even with identical inflator designs, the likelihood of a potential rupture is greater in certain vehicle models … due to factors that have not yet been identified,” the report said.