CHARLOTTE, N.C. - It started with a small gesture by Graham Rahal, who wanted to raise money for Dan Wheldon's family by auctioning off his helmet from the IndyCar season finale.

He announced his intentions on Twitter and the response from the motorsports community was immediate and overwhelming. It didn't take Rahal long to realize he alone couldn't handle the outpouring of support for Wheldon, the two-time Indianapolis 500 winner killed in the Oct. 16 race at Las Vegas.

More than US$200,000 had been raised by Wednesday, the ninth day of the auction, with many big ticket items yet to be posted. One hundred per cent of the proceeds will go to a trust fund established by IndyCar for Wheldon's wife and two young sons.

"I thought we would have a lot of support and a pretty good turnout of people saying 'We'll give this' or 'We'll give that,' but for it to get as large as it has — nobody ever expected this," Rahal said Wednesday.

"It's been pretty cool. I think it shows how tightknit the sports community is overall, it isn't just racing."

Rahal didn't have any idea what it would become when he decided to auction off his helmet, which had a special design to celebrate the Las Vegas finale. Pledges of memorabilia from other IndyCar drivers came within minutes of him posting his plan on Twitter, and within a day, it had transcended far beyond their small community.

"It really went crazy, and I think right away we realized this was getting to a size that was more than my girlfriend and I could run out of the house," said Rahal, a driver for Service Central Chip Ganassi Racing.

"We had everybody sending items to the house and it was like, 'Holy smokes, what are we going to do now?' "

NASCAR drivers began donating items within a day, and before the week was over, Rahal had a pledge for a Tour de France jersey from Lance Armstrong, a surfboard from Kelly Slater and interest from celebrities and athletes around the world.

It turned into a fast lesson on what can be accomplished through social media.

After enlisting help with the auction — GoDaddy.com got Rahal with eBay, which waived all fees, and Auction Cause, a Los Angeles-based auction management agency — Rahal, girlfriend Laken Kurtz and Beccy Gordon, the wife of IndyCar driver Ryan Hunter-Reay, had a conference call to figure out how to publicize the auction.

They decided to stick with Twitter, which was already working so well. Gordon established a Twitter account — (at)DWheldonAuction — and it quickly became the fastest-growing charity handle to date on Twitter. With over 4,000 followers within 20 minutes of launching, the account now has almost 13,000 followers who are alerted each evening to the newest items added to the auction.

"It's the little auction that could," Gordon said. "It started with Graham saying on Twitter he was going to auction off his helmet. He probably would have gotten a sponsor to buy it for $5,000 and donate it to the Wheldon family. Now we're overwhelmed. It's proof that people are spending extra money to help a good cause."

Rahal said he initially thought he might be able to raise about $150,000. Now, he doesn't dare guess at what the final total will be. Bidding on five-time NASCAR champion Jimmie Johnson's race-worn helmet has reached $20,000, and Rahal's father, Bobby, donated the last helmet he had in his personal collection and bidding is over $10,000.

Still to come are firesuits from NASCAR driver Kyle Busch, a ton of memorabilia from Formula One drivers, and the Rahal helmet that started the whole thing.

Gordon said pledges for items are still coming in, but the trio has started discussions on bringing it to a close.

"There has to be an end point somewhere," Gordon said. "People are still calling us with donations, and it could keep going forever if we wanted to. But we should probably need to figure out when it's going to end."

Rahal, who said he checks the site repeatedly throughout the day to see how much money has been raised, marvels at the items being auctioned and the scope of the bidding.

"We got this racing suit from (F1 champion) Fernando Alonso, and in two days it was at like $10,000. That's absurd," Rahal said. "But I think Dan touched people on more than a local and national level. He touched people all over the world, and we have items that can reach those people who loved Dan."