BALTIMORE, SEPT. 21 -- State highway traffic engineers are circulating a study concluding that speed limits can be raised from 55 to 65 miles an hour on most of Maryland's 166 miles of rural interstate roads without endangering drivers, a position opposed by Gov. William Donald Schaefer.

The study, resulting from congressional action in March that changed the national 55 mph law adopted in 1974 as a fuel conservation measure, could trigger a fight between Schaefer and rural state legislators when the Maryland General Assembly convenes in January to consider raising the limit.

But the study, at least in its present draft form, may not go far beyond the traffic engineers' work table. Hal Kassoff, head of the state highway administration over the engineers, said yesterday that he is "very skeptical about the wisdom of raising the speed limit."

He added, however, that he wanted to see the study in its final form and analyze traffic accident data of other states that have adopted a 65 mph law before a final decision is made about the engineers' study.

No 65 mph proposal has been floated so far by state legislators, but various road user associations are expected to push for higher limits now that Congress has amended the law to permit states to raise speed limits to 65 on rural interstates. At least 37 states have done so. Virginia, like Maryland, has not acted.

Any attempt to increase speed limits in Maryland is expected to meet resistance from law enforcement agencies and the National Safety Council, which historically have argued that greater speeds cause more accidents and deaths.

The nine-page Maryland study says the engineering design and relatively low traffic volume on most rural segments of Maryland's interstate system "are consistent with safe operating speeds of 65 mph."

It cited four segments it consid- ers eligible: I-270 in Montgomery County north from Rte. 118 almost to Frederick; I-95 northeast of Baltimore just outside the Baltimore Beltway to near the Delaware line; I-70 west of Baltimore from Rte. 29 to the Pennsylvania line, possibly excepting short segments around Frederick and Hagerstown, and I-83 north of Baltimore from Shawan Road to the Pennsylvania line.

Most other segments of the state's 381 miles of interstate highways are classified as urban, including the heavily used I-95 section between Washington and Baltimore and the beltways around the two cities, and therefore they are not eligible for increased speed limits under the federal law.

Citing widespread disregard of the current 55 mph limit in Maryland, the study said 65 is more reasonable and realistic and is not likely to increase average speeds or cause more accidents.

Schaefer has flatly opposed any speed limit increase. "I don't favor it," he told reporters last month.

" . . . When you go 55, they go by you like you are standing still. So if you go up to 65, they'll go by you like you are standing still."

But Thomas Hicks, chief traffic engineer in the highway administration under Kassoff, said he thinks that the governor's "mind is still open" and that he may find the study reasonable.

While there are reportedly differences of opinion among various engineers in the highway administration, Hicks, who favors raising the speed limit, said he hopes to produce a final version of the study soon.

The draft says that increased accidents are not caused by greater speeds so much as by variances in speed, such as cars going either much faster or much slower than the bulk of the traffic. A reasonable speed limit would be one set at the so-called 85th percentile speed -- that is, the speed below which 85 percent of the traffic is traveling, the study said.

On rural interstates in Maryland, that is about 68 mph, the study says.

The study cited preliminary reports in California that the 85th percentile speed has increased only 2 mph since a new 65 mph law was adopted there.

But similar statistics in New Mexico suggest an "alarming increase" in serious accidents and injuries since the higher limit went into effect, according to the National Safety Council.