OXFORD — For only the third time in nearly 50 years, ownership of the region’s largest sports entertainment facility is changing hands.

Bill Ryan announced Sunday afternoon that he has entered into an agreement to sell Oxford Plains Speedway to Tom Mayberry of Naples.

The deal is expected to be finalized within the next week.

“(Mayberry) is a superb promoter and has great ideas and passion and will undoubtedly continue the success that we have had over the years,” Ryan said in a news release. “I am confident that under Tom’s leadership the speedway will thrive.”

Mayberry is the founder and promoter of the Pro All Stars Series, one of New England’s most prominent racing tours since 2001.

Prior to that he was a successful racer at the speedway.

“Obviously, I grew up attending races at Oxford Plains and eventually was able to race there myself,” Mayberry said in a separate statement. “We hope we can continue the great tradition at Oxford and are looking forward to a bright future. I’m looking forward to working with the competitors and the fans, and I hope to have their support.”

The transition will dramatically transform the speedway’s showcase race, the Oxford 250.

After six years as a late-model event with rules parallel to those of Vermont’s American-Canadian Tour, the 40th annual summer classic in 2013 will mark a return to PASS super-late-model standards, Mayberry said.

Mayberry announced Sunday that the 250 weekend will take place from July 19 to 21, 2013. In keeping with tradition, all qualifying for the main event will be held on Sunday.

PASS also left the door open for other late-model cars to compete in the event.

“Rules are being adjusted at this time so various competitors can make their cars legal if they wish to compete,” according to the release.

Oxford’s reigning late-model champion, Shawn Martin of Turner, expressed concerns that the format change could make his car obsolete for the race.

“I can’t build my car into a super late model,” Martin said. “Guys like (2012 OPS points runner-up) Travis Stearns and myself, we’re on a budget. We can’t compete with a lot of those teams.”

Despite the bristling from many drivers and fans, Oxford’s restructured late-model division grew into the largest headline class of any track in Maine.

Martin topped a division that averaged more than 25 cars per Saturday night. More than 70 late models have attempted to qualify for one of 38 spots in the TD Bank 250 every year since 2007.

“Tom is a racing guy, and he’s a smart guy,” said Shane Green of South Paris, who has raced at Oxford for more than 30 years. “He’s not just going to tell 25 late models they don’t have a place to race. My reaction is that I’m going to wait and see what he says.”

Previous changes in Oxford’s weekly and 250 formats led to an on-again, off-again and at times contentious relationship between Ryan and Mayberry over the past decade.

OPS and PASS were loosely affiliated until 2006.

That summer, Ryan made the announcement that he was disbanding two of the top three weekly divisions at the track — pro stock and limited sportsman.

Ryan also changed the format of the Oxford 250 from pro stock to late model. It effectively ended the track’s relationship with Mayberry’s PASS and aligned it with Curley’s ACT.

But pro stock racing — also known as super late model, the touring division’s attempt to distance itself from the less powerful cars of its competition — maintained a strong foothold in Northern New England and Eastern Canada.

Mayberry and Ryan mended fences in 2011 and have co-promoted successful 150-lap races on the eve of the 250 each of the past two summers.

Many well-known PASS drivers — including Mike Rowe of Turner, Cassius Clark of Farmington and Johnny Clark of Farmingdale — have been infrequent competitors at the historic 3/8-mile oval since the initial departure of pro stocks six years ago.

This season’s final PASS race of the season at Oxford has twice been postponed by rain. It is now scheduled for Saturday, Oct. 20.

Ryan purchased partial ownership of the track from Gray real estate developer Michael Liberty in 1998. He took over completely in 2000.

Liberty previously took the reins from Bob Bahre, who ran OPS from 1964 to 1986 before building New Hampshire Motor Speedway.

A native of Massachusetts and a graduate of Williams College, Ryan was a sports marketing attorney before his stint at Oxford.

The Falmouth resident also is a majority owner of the Maine Red Claws, an NBA Development League basketball team based in Portland.

Oxford’s weekly car count and attendance more than doubled during Ryan’s early management, thanks in part to the addition of a thriving Wednesday race program

Under Ryan’s leadership, the Oxford 250 had attracted at least one active NASCAR driver every year since 2004. Sprint Cup stars Matt Kenseth, Kurt Busch, Kyle Busch, Kevin Harvick and Denny Hamlin were among the luminaries to run the race.

Harvick (2008) and Kyle Busch (2010) each won it.

While that event remained a major attraction in the region, sluggish economy and the ongoing fallout from the decision to drop pro stocks took a toll on weekly attendance.

“I am proud of what we have accomplished over the last 14 years. I want to thank all the fans, drivers, teams, employees and partners for their support,” Ryan said.

Mayberry said that the 2013 OPS season will begin April 20 and that an Oxford 250 schedule will be released by Dec. 1.

He added that any division and rules changes for the weekly program will be announced by Nov. 5.

koakes@sunjournal.com