Last week Erwin was replaced at Roush by Matt Puccia as Biffle's crew chief, as the leading Ford outfit attempts placing all its four drivers in contention for a Chase birth.
Allmendinger currently ranks tied 16th in the point standings and a victory in the following seven races could potentially put him in position to take a wild-card entry into the playoff.
Richard Petty Motorsports has a close technical relationship with Roush Fenway Racing, which was likely a key factor in Erwin taking over from Mike Shiplett as the crew chief of the iconic #43 RPM Ford.
"Mike and I have been together for a long time, so from a personal standpoint this is difficult for me," said Allmendinger. "We've worked really well together and I think our personalities really complemented each other. Mike and I both came into this year really committed to working on our weaker areas.
"I know we both tried our best to be better and communicate better - I couldn't have asked for either of us to try any harder. Sometimes though, you need to take a step back and have a new perspective or new set of eyes look at things to move to the next level.
"Greg Erwin is a really talented crew chief and we're lucky to have him come on board with us," continued Allmendinger. "He has had a lot of success, brings a fresh perspective and has shown he knows exactly what it takes to win. I'm looking forward to seeing what we can do together and taking the team to that next level."
Erwin led Biffle to five victories, while three times they were Chase contenders since their first full season together in 2008, finishing third in point standings that year.
"When one door closes, another one opens and this is a great example of that," said Erwin. "I couldn't be happier to have found a new home at Richard Petty Motorsports. To work with Richard Petty and lead the iconic #43 team is a great opportunity for me. AJ Allmendinger has shown that he has a great deal of talent and I'm excited to have the chance to get the No. 43 team back to victory lane."
Allmendinger currently ranks eight points behind Biffle in the standings as both attempt to be playoff contenders.
