The tires were cut Sunday outside Fayetteville's Crown Coliseum, The Fayetteville Observer reported Monday.
Cumberland County Sheriff's spokeswoman Debbie Smith said Monday afternoon there were no suspects, but the case still was being investigated.
Campaign representatives for Obama and Republican opponent John McCain said they weren't aware of the incident.
Lynne Steenstra said it cost $120 to get her van towed and repaired. Steenstra said she was concerned that the slashing might be a scare tactic to harass Obama supporters.
"It hasn't deterred us one bit," Steenstra said. "It has only encouraged us more. I just hope whoever did this pays the price."
Obama's North Carolina campaign spokeswoman Susan Lagana said it was disappointing that the candidate's supporters had to experience the vandalism.
Sarah Revis lives on Wilkes Road where most of the tires were slashed and said she saw a single mother and a toddler stranded.
"This is an embarrassment to this city and to me as a citizen," Revis said.
Earlier in the day, the newspaper said, Obama visited a local restaurant where one patron shouted "Boo, socialist! Socialist! Get out of here!"
Other patrons clapped and Obama walked through the dining room shaking hands before leaving to attend the rally. Obama also spoke to the woman who shouted at him.
Monday, Grammy award winner and Chapel Hill native, James Taylor, will be singing /*Barack Obama*/'s praises.
Sunday night he performed in Charlotte, and today he will be in Chapel Hill.
During Sunday's Fayetteville rally, Obama talked about a middle class economic bailout package for North Carolina. "Let's open those old textile mills, turn them into solar panel manufacturing plants, turn old tobacco fields into other crops to turn out ethanol to fuel the cars of the future."
Afterwards, he spoke exclusively to /*Eyewitness News*/.
"I know here in NC i's tight as a tick, and we are just going to have to work as hard as we can make sure the people are turning out [for] early voting, and I think obviously its a great help," Obama said. To watch the full interview, click
Taylor's performance is scheduled for 5 p.m. at Fetzer Field on the UNC campus. He'll also hold concerts at Moore Square in Raleigh and in Wilmington. Tickets are required for the Chapel Hill performance and be picked up at the planetarium on Franklin Street.