The national speed limit on Runshaw Lane would be reduced to 40mph, with a new 30mph speed limit from near Glencroft to near the junction with Primrose Hill Road.
Last month newly-engaged couple Alex Wilson, 23, and Kirsty Belsham, 22, died after a car crash on Runshaw Lane, leaving two young children.
Alex’s grandmother Elspbeth Wilson does not believe Kirsty was speeding and said she had a black box in the car for insurance purposes.
But she supported the plans to reduce the speed limit on Runshaw Lane.
Elspbeth, of Bispham Avenue, Farington Moss, said: “I think anything that makes it safer for drivers has got to be a good thing. I have been up that road myself and I know what people are like.”
A speeding driver was jailed in December after colliding with cyclist Daniel Richmond on Runshaw Lane in April 2014, causing fatal injuries.
People living on Runshaw Lane have been campaigning for years for a lower speed limit and road safety measures.
County Coun Mark Perks, whose Chorley North division includes Runshaw Lane, said the reduced speed limit was “long overdue”.
He said: “We can’t physically stop motorists who want to break the speed limit, but reducing the speed limit should make people think that speeding can lead to deaths.”
Concerns about Runshaw Lane were raised on social media following the crash involving Kirsty and Alex.
Ridwan Musa, highways manager for Lancashire County Council, said: “We’re proposing to reduce speed limits on a number of roads in Chorley following discussions between our engineers and police about road safety concerns.
“We held a formal consultation on these proposals at the end of last year and will present a report to the cabinet member for highways and transport for a final decision in May.”