How To Measure A Race Track
First, we need to know how to measure a race track. Obviously if you run up around the outside wall you are traveling significantly farther than if you are down at the bottom of the turn. So how does NASCAR measure? They measure track length from the point 15-feet in from the outside wall. This means that at many tracks the drivers are traveling a shorter distance than advertised (but not by much).
The Problem With Race Naming
Now that we know how to measure a track, what does that tell us about the Sharpie 500 vs. the Aarons 499? Nothing yet. Let's look at race distance.
The number at the end of the race name could be talking about laps, miles, or even kilometers! NASCAR works with the tracks to find an appropriate race length that fits nicely into a TV window. So just by hearing that the race is called the Checker Auto Parts 500 you don't really know how far the cars are going to drive without more research.
One Vote For Miles, Rounded Up
Talladega Superspeedway measures a massive 2.66 miles. High speeds there mean that 499 miles can be covered nicely in a TV window. At Talladega if the race were 187 laps long they would only have covered 497.42 miles while 188 laps is 500.08 miles so which do they use? NASCAR always rounds up so the Aarons 499 is 188 laps long and actually goes 500.08 miles. It's a nice marketing trick that 499 miles is exactly the same race distance as 500 miles at Talladega.
One Vote For Laps
Bristol Motor Speedway measures 0.533 miles around. Because of the slower speeds of the short track it works out that 500 laps makes the best race distance. So the Sharpie 500 in Bristol is actually 266.5 miles long.
As a rule of thumb, short track races are measured in laps, most everything else is measured in miles. There are some exceptions but you'd mostly be right with this rule.
An Exception To The Rule
One of those exceptions is Phoenix International Raceway. Every fall they run the Checker Auto Parts 500 on the 1 mile oval. Easy right? Since 500 laps equals 500 miles then that must be the answer. Nope, sorry. It turns out that it takes too long to run 500 miles on the relatively flat track so NASCAR got creative there and declared the official race distance to be 500 kilometers. So the Checker Auto Parts 500 in Phoenix is actually 312 laps and 312 miles long.
Road Courses Shoot For 350 Kilometers
Road racing is a whole different ballgame. NASCAR tries to run the Cup cars approximately 350 kilometers (220 miles) for road races. The Dodge/Save Mart 350 at Infineon Raceway on the 1.99 mile road course comes out to 110 laps and they actually travel 352.3 kilometers.
Finally, the Sirius at The Glen on Watkins Glen International's beautiful road course. They don't even pretend to tell you how long the race is. They typically run 90 laps on the 2.45 mile "short course" at The Glen which makes the total race distance 220.5 miles or 355.005 kilometers.
Summing Up The Rules
Confused yet? Just remember, short tracks are laps, speedways are miles, road races are kilometers and the people in Phoenix must be crazy because they're breaking my nice rule.