What to know if it rains during the IndyCar GMR Grand Prix at Indianapolis Motor Speedway

The ninth running of the GMR Grand Prix at the Indianapolis Motor Speedway is set for Saturday, May 14. With the green flag expected at 3:45 p.m., there are looming questions about the weather.

Current forecasts for Saturday show a high of 83 degrees but a 70% chance of rain. Thunderstorms are expected in the afternoon, meaning the race could be affected by rain. Here is what will happen if it rains during the Grand Prix:

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Can Indy cars race in the rain?

Yes. It is not uncommon for road course races to take place during rain. There is, however, a threshold of rain that could cause a postponement or early ending. In a light rain situation, IndyCar can declare the race "wet," which will neutralize the requirement of running on both the black primary and red alternate tires. If the track dries out during the race, teams can elect to put on slick tires of any compound at their discretion.

What happens if there's a downpour at an IndyCar race?

If the rain is too hard or if visibility is too low, IndyCar may elect to throw a caution until conditions improve or stop the race altogether.

When is an IndyCar race official if it's stopped due to rain?

A race can be declared official if half of the distance has been completed. That means in Saturday's 85-lap race, 43 laps must be completed before IndyCar can end the race and have official results. If the race has not reached halfway, the race can be completed on the next available day.

Could the Indy 500 run in the rain?

The short answer is no. The reason why rain races are feasible on road and street courses is because of their lower top speeds compared to an oval race. Rain races typically have a slower pace and earlier braking points. In an oval race, where there can be little to no braking, the cars are simply going too fast to be able to safely navigate a wet race course. Even on rain tires the speeds are too high for a safe race to be contested on an oval.

Should teams be worried about tire shortages?

Friday's practice and qualifying sessions took place in fully dry conditions. Teams shouldn't need to worry about running out of available sets of wet tires as the first time they would use them would likely be on race day if it rains. Even if the race is declared "wet" and rain tires are mandated for the start, teams should have enough sets to last the entire race, even with a three-stop strategy.

What should fans do if it rains?

Be prepared. With thunderstorms likely, it is now a common safety practice to evacuate the grandstands if lightning strikes in the general area of the track. Even if the lightning strike is more than a mile away, the grandstands could still be evacuated for safety reasons. Race fans should bring ponchos and umbrellas with them in the event of rain. It is unlikely fans will be allowed to take shelter under the grandstands if there is lightning in the area.

This article originally appeared on Indianapolis Star: IndyCar GMR Grand Prix: What to know if it rains at IMS on Saturday