The Detroit Pistons have signed Australian big man Aron Baynes to a reported $A26.36 million deal.

Baynes spent the past three seasons at the San Antonio Spurs, winning the NBA title alongside fellow Australian Patty Mills last year.

Baynes, in a tweet, thanked the "Spurs family" on Thursday and declared: "Motor City!!"

"Appreciate the support over the last three years," Baynes wrote.

"I loved my time and will always remember the great team and community."

The three-year contract is a big pay rise for the New Zealand-born, Queensland-raised Baynes who earned $2.62 million last season with the Spurs.

The Spurs used the 28-year-old at centre and forward in which he averaged seven points, five rebounds in 70 games in 2014/15.

The Pistons have not fared well in the weak Eastern Conference in recent seasons, but Baynes says the team is on the way up.

"I'm really excited to have the opportunity to play with Detroit," Baynes told Basketball Australia (BA).

"I can't wait to work with the great coaches and players already at the club.

"We are going to surprise some people."

Baynes' agent Daniel Moldovan says deal is just reward.

"Aron has come a long way in the last few years," Moldovan told BA.

"He had a great experience with a first-class organisation in San Antonio and this is another exciting step in his career.

"I'm happy that he is being rewarded for all his hard work and dedication."

The Spurs are pursuing the marquee free agent LaMarcus Aldridge, who is expected to not return to the Portland Trail Blazers.

There are reports if the Spurs do snare Aldridge the team could deal Mills and some other Spur bench players to clear salary space for Aldridge's big contract.

Mills sent Baynes a tweet congratulating him on the Pistons deal and promised to send him some of San Antonio's famous barbecue "whenever you miss it".

AAP