In their headlong dash to prosperity, "the four tigers of Asia" stumbled badly last year.

Those newly industrialized nations (NICs) of the Pacific Rim -- Hong Kong, Singapore, South Korea and Taiwan -- gained that nickname because of their runaway economic growth of about 9 percent a year for the past two decades.

They suddenly find themselves in an unaccustomed position of having sharply lower growth rates, or even declines.

Their weak 1985 economic performances, moreover, spawned a sudden reevaluation of the potential of the entire Pacific Rim -- the five less-developed nations of the Association of Southeast Asian Nations (ASEAN), as well as the "four tigers."

The notion that the 1980s and beyond will be "the era of the Pacific" runs deep here in California, which sees its future prosperity linked to the growth of that part of the world.

This view was fueled when the Pacific recently surpassed the Atlantic as the leading route for trade with the United States.

"There tends to be on the West Coast a Pacific fever that has grabbed the policy-making community and the business community," predicated on the idea that the rim has "unlimited growth potential," said Peter Woolitzer, assistant director of the Institute of International Studies at the University of California at Berkeley.

"It makes everyone salivate," he said.

Now, however, "The realities are beginning to settle in," said Richard Kjeldsen, international economist with Security Pacific National Bank here, who long has taken a cautious view of the Pacific Rim phenomenon.

"You have to recognize the new realities of lower growth, [the need to] catch up on financing, and the possible flashpoint that the growth of protectionism would hurt them," Kjeldsen added.

"The Pacific Rim scenerio is not going to go away, but it's going to lighten up. I don't see people waving flags anymore," said Charles H. Nevil, a Los Angeles-based trader and member of the California World Trade Commission who has been dealing in Asia for more than 20 years.

The reason for the slowdown among the Pacific NICs is simple. All four "tigers" have been battered by last year's slowdown in economic growth in the United States, the leading market for the manufactured goods that fueled their rapid expansion.

"Their exports to the United States are not up as much in 1985 as they were the year before, said David Lund, an international economist with the Commerce Department.

"It's not a negative, it's the absence of positive" that is slowing them down, Lund said.

The United States buys, for example, half of Taiwan's imports, 44 percent of Hong Kong's, 40 percent of South Korea's and 20 percent of Singapore's.

The ASEAN nations -- Malaysia, Indonesia, the Philippines, Brunei and Thailand -- suffer from the same problem, with the addition of a sharp lowering of the price of commodities such as tin, rubber and oil that underpin their economies.

Country by country, here is the outlook for the four "tigers" of the Pacific Rim:

*Singapore is likely to have suffered its first year of decline since 1964, a shock made worse when compared with its more than 9 percent growth in 1984, when the United States seemed to suck in imports.

Exports from that city-state on the tip of the Maylay peninsula dropped an estimated 18 percent last year as the effects of a slowdown in the U.S. electronics market were felt.

Also, that nation's economic performance was worsened by the slack in the world oil market, which hurt Singapore's refinery products.

"They are losing their edge in another area because labor costs got so high they are at a competitive disadvantage with Korea and Taiwan and they have had difficulty in moving up the technology hierarchy," said Kjeldsen.

"No one is making the case anymore that they are following Korea up the ladder."

*Korea's government says its growth rate slipped to 5 percent in 1985 from a booming 7-plus percent in 1984, but private specialists believe the economy was even more sluggish, growing at a rate that could have been as low as 3 percent.

The government remains optimistic for this year, predicting 6 percent growth.

Bankers, however, sound a more cautionary note.

They are concerned by Korea's high short-term debt, which financed its growth while making it one of the major debtor nations.

The caution persists even though Korea has a perfect payment record.

"We've seen too many countries go from very good ones to ones going over the edge. Korea has gotten bankers' attention as a country that could have problems," said one banker here.

*Hong Kong faces more than economic problems. Its privileged position as a British crown colony ends in 1997, when China takes over, and there are concerns that a communist government will crimp Hong Kong's laissez faire economic style, despite Peking's assurances to the contrary.

Meanwhile, last year's growth rate is estimated at half or less of the booming 9.6 percent growth recorded in 1984.

Exports grew by only 1 percent instead of 1984's 17 percent and the original prediction of 11 percent.

*Taiwan also faces sharp decreases in its export performance, as well as structural problems exemplified by the collapse of major investment institutions.

The government reported last year's growth at 6 percent, but private economists place it somewhat lower -- between 4 percent and 5 percent.

That is a precipitous drop from the 1984 rate of 10.9 percent, the highest growth since 1978.