U.S. auto safety regulators said Tuesday they would investigate the performance of a Continental Tire model that is part of Ford Motor Co.'s plan to replace 13 million Firestone tires on all its vehicles.

The General Ameri+550AS P235/70R16 is made by Continental Tire North America, a unit of Germany's Continental AG , and is among 11 tire models in the $3 billion Ford plan that were questioned by Congress and reviewed by the National Highway Traffic Safety Administration.

Ford defended the performance of the tire used on its popular F-150 pickup truck, but said it would remove it from its replacement list until the government completed its investigation.

The auto giant is using 60 tire models in its replacement plan, and said the Ameri+550AS represented less than 0.1 percent of the replacement tires it planned to use. Ford said 4,300 of them had been used as replacements so far.

Safety regulators raised no objections to the 10 other replacement models it reviewed. However, they left open the option of investigating them later if there were cause to do so.

Ford said in May it would replace Firestone Wilderness AT tires on all its vehicles after losing confidence in the tiremaker following last summer's recall of 6.5 million tires, which included certain Wilderness ATs.

Many of the recalled tires were installed as standard equipment on Ford Explorer sports utility vehicles, and have been linked to crashes that occurred after tire blowouts and tread separations.

NHTSA, which completed a massive investigation into Firestone tires last week, linked 203 deaths and hundreds of injuries to defective Firestone tires.

Continental said in a statement that it had shipped more than 2.7 million Ameri+550s since 1996, mainly for use on the F-150 pickup.

NHTSA said the tire had a tread separation claims rate of 124 per million, which the government said "exceeds that of any other tire" reviewed by investigators.

The agency said the Ameri+550 data included seven crashes that included two rollovers and 17 injuries. However, the company said the tire's performance was "excellent," listing only three accidents that caused injuries and one lawsuit that was settled long ago.

There have been no fatalities associated with the tire, according to Continental, which disputed the accuracy and relevancy of the claims-rate figure. The government, Continental and Ford agree that claims data alone is not enough to calculate safety.

"The Ford F-150 is a pickup truck used in off road conditions and difficult environments, such as construction sites," Continental said.

"The Ameri+550AS adjustment data must be viewed in the context of its application and the environment in which it is placed. It cannot be compared with data from other tires, such as passenger tires, and it is misleading to consumers to make generalizations about safety records based on comparing only one set of data," the company said.

Nevertheless, the government said to "assure that relevant information is not missed" it would investigate the entire population of the Ameri+550AS.

"NHTSA emphasizes that the opening of this defect investigation does not mean that (investigators) have concluded that these tires contain a safety-related defect or that they are not 'safe.' Rather, it reflects a decision that issues have been raised that warrant further investigation by the agency," the statement said.

Other tire manufacturers supplying replacement tires to Ford include Goodyear Tire & Rubber Co. and Michelin, which also sells tires under the BF Goodrich brand.

Firestone is a unit of Japan's Bridgestone Corp.