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McALLEN, Texas (CNN) -- Attorneys for Bridgestone/ Firestone attempted Thursday to cast doubt on the testimony of a tire expert who said one type of the company's Wilderness AT tires was sub-standard and responsible for an accident that seriously injured a Texas mother.

Marisa Rodriguez, 40, of Pharr, Texas, and members of her family sued Firestone for $1 billion after an accident last year in which their 1998 Ford Explorer rolled over on a highway in Mexico after the tread on the right rear tire separated.

Firestone attorney Scott Edwards grilled tire expert Robert Ochs about his testimony Wednesday that the tires were defective. Edwards zeroed in on Ochs' comments that the tires did not have nylon caps, which help to keep the tire temperature down.

Edwards said that between the mid-1980s and mid-1990s, 90 percent of steel-belted radial tires did not have such nylon caps. He demanded to know whether Ochs, an engineer from New York City who once worked for Michelin, believed all those tires were defective.

"No, what I'm trying to tell the jury, this line of tires was defective because it did not have nylon cap plies," Ochs said of the Wilderness AT line.

At one point, Edwards sought to shift blame to the Explorer, asking Ochs if he would want "one of (his) primary family members driving a Ford Explorer."

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"No, I would not," Ochs said.

In redirect, the lead plaintiff attorney, C. Tab Turner, asked Ochs if he had ever seen a tire like the Wilderness AT that had tread-belt separation that had caused so much damage.

"Not at this magnitude, no," Ochs said.

Have you ever seen a group of tires cause such "catastrophic damage" in southern states?

"Again, on this order or magnitude, no," said Ochs.

Rodriguez, who has been confined to a wheelchair since the accident, is expected to take the stand later Thursday, as well as her husband Joel .

Marisa Rodriguez is confined to a wheelchair as a result of the accident

The March 9, 2000, accident occurred five months before Firestone announced it was recalling 6.5 million 15-inch Wilderness AT, ATX, and ATX II tires manufactured at Firestone's Decatur, Ill. plant -- where the Rodriguezes' tire was made.

The Rodriguez family reached an undisclosed settlement with Ford in July.

The National Highway Traffic Safety Administration has documented 203 deaths and more than 700 injuries linked to tread separation rollover accidents involving the tires and Ford Explorers.

Bridgestone/Firestone chief executive John Lampe is expected to be called as a defense witness, possibly on Friday. Lampe has already testified in a videotaped deposition.

-- CNN Correspondent Ed Lavender and Producer Carol Yancho contributed to this report.