Rain limits final Indy 500 practice

They said the Carb Day session is usually little more than a leak check and the handful of laps they got in before the rain was enough.

"My theory is that if you don't know it by Carb Day, you're never going to have it," said Dan Wheldon, who will start second on Sunday and was fastest during Friday's shortened session.

"You can certainly fine-tune it in the race with all of the pit stops you have. The balance seemed nice today. Let's just hope it's like that Sunday."

The fastest of Wheldon's six laps in the No.10 Chip Ganassi Racing car was 223.934mph, 0.26 seconds better than team-mate and pole winner Scott Dixon, who had the second-best lap.

"All of us want to get out there and race," Dixon said. "We did three laps at speed. It's hard to tell. Nobody is really running, nobody is really in traffic. I think the other group that was behind us later on got a bit of a run in traffic. I know Dan did.

"We learned a couple things with our fuel and things like that, but nothing that's really going to lead to too much of an asset."

Others near the top of the speed chart included Vitor Meira, third-best of the session at 222.326mph in the No.4 Panther Racing car, and Tony Kanaan, fourth-fastest at 222.130mph in the No.11 Andretti Green entry. John Andretti, the surprise of the month, was fifth-best in the No.24 Roth Racing car.

"I don't know if we have it right," Andretti said. "We certainly tried to build as much grip in it mechanically. It still seems pretty good. The car has plenty of grip, but I don't know. Nobody knows.

"I think there are a few guys that will run off and leave everybody. I just hope to be a part of that second group of guys that can hang on."

Leading the group expected to run away could be Wheldon, who isn't likely to get much of a battle from Dixon, who said on Friday that he intends to be cautious at the start.

"If (Dan) wants to lead, he can lead," Dixon said. "Whatever happens from the start, we're just going to take it cautiously and make sure we get through it and try to maybe sit back a little bit. We'll see what our options are. I want to see what the car is like in traffic early on, as well. We're just going to see what comes."

The rest of Friday's activities were washed out. The pit-stop competition was cancelled, and the Freedom 100 Indy Lights race was postponed until Saturday.

Weather forecasts for Saturday and Sunday appear positive, with mild temperatures and sunny skies.