A major review of speed limits on A and B roads is to take place.
More consistency is sought by ministers on speed limits
Traffic authorities in England, Scotland and Wales are being asked to conduct reviews which could see 60mph limits coming down on many rural roads.
The review could also see some limits going up from existing levels if safe, but it will not result in new national limits for motorways or built-up areas.
Ministers want more consistency in speed limits on single and dual carriageways that are not trunk roads.
These are commonly in rural areas and typically under local council control, which means varying limits can be set on similar roads in different places.
The Department for Transport in England, and the Scottish and Welsh transport authorities, said they wanted "realistic and consistent" limits, that kept traffic moving, in place by 2011.
This could result in the lowering of speed limits, but it could also see limits going up if it is safe.
The government says drivers should instinctively understand new limits on local roads.
Transport minister Stephen Ladyman said: "Our new guidance encourages lowering speed limits where the evidence warrants it but equally traffic authorities should consider increasing limits if it can be done safely."
A Department for Transport spokesman said local authorities had not been given any specific instruction: "one way or another."
"We're not saying you can go above 70mph or below 20mph and many of the limits are already appropriate.
"But lots of the roads are now better designed and have been re-engineered since the limits were set. Some have had traffic lights put in, for example."
Edmund King, of the RAC Foundation, said consistency was needed: "We do have some limits on A-roads, where there isn't pedestrian or cycle access, where the limit is 40mph, whereas in other cases they would be 60mph.
"But there are country roads going through villages where the limit is 60mph, when it should be 30mph.
"An important point to make is that just because a limit is set doesn't mean the driver has to travel at that speed all the time."
However, Bert Morris of the AA Motoring Trust is unconvinced that the proposed review would prove useful enough and he wants all speed limits to be scrutinised along with road conditions.
"Putting it at a lower speed limit rather than maintaining the road properly may not be the answer to deal with an accident problem," he said.
Sean Spiers, chief executive of the Campaign to Protect Rural England, said there is a strong demand for the review.
"Fifty seven per cent of fatalities on the road last year were in rural areas, so there is a crying need for this and we know that lots of villages are lobbying their local authorities to introduce thirty mile speed limits."
Under the current system, the default national speed limit is 30mph on lit urban roads, 60mph on single carriageway roads and 70mph on dual carriageways, as well as motorways.