Despite living in the south and growing up just down the road from Darlington, SC, about all I know about Nascar is that it involves cars driving in big circles at high speeds so I’m not up on all that it involves.
Yesterday, during lunch, the restaurant I was in was showing a race on their big screen and I kept seeing cars pulling into their pits and changing tires.
If I understand correctly, these races are like 400-500 miles in length. Now, the tires on my car are rated for 50,000 miles and I’ve seen them even higher. Even given the differences in speed involved, why are the tires on these cars wearing out over 100 times as fast as the ones on my car? Are they that different? Why can’t they just put a 500 mile tire on these things and save the effort of a bunch of guys running around with air guns?
It varies from track to track. At Talladega, they can actually go the whole race without changing tires. At Darlington, the track is rough (you live down there, think about the secondary roads. That’s what the track looks like.) and the tires wear out quick. They are going through the corners around 120 mph, maintaining a controlled slide. If you took your car and went out in a parking lot and did a constant donut, your tires would wear out in a matter of minutes. The pit window at Darlington is about 60 laps, IIRC.
Race tire are made just for racing (they are NOT legal to drive on on a public road BTW)
They are wider, have very thin sidewalls, and the rubber compound is very soft.
These tires are designed to heat up and this heat actually makes the rubber get sticky. Also having no tread, if any water gets on the track (rain) they loose all traction as they have no grooves to drain away water.
If you tried to run street tires on a NASCAR car (or any other race car using racing tires) You would find the following things would occur
[ul]
[li]You would lose. You could not build the G forces that a race tire does and that means you go slower in the turns.[/li][li]The tire would probably fall apart at speed from over heating (not a good thing)[/li][li]The damn things won’t last anywhere near 50,000 miles.[/li][li]Did I mention you would lose the race?[/li][/ul]
Hmmm… Interesting. I knew the tires they were using were different than normal tires but I didn’t realize the difference was that substantial. I certainly didn’t realize they had no tread.
For some reason I thought the purpose of treads on tires was to increase traction; your posts seem to imply otherwise. Or is this another case of different tires for different purposes?
Ah well, I knew there had to be some reason, I just couldn’t figure out what it was. Thanks.
On a dry road the more rubber on the road, the better traction. In the rain you need tread to move the water out from under the tire, or the tire will hydroplane (again not a good thing)
Steet tires have tread because you don’t have a pit to pull into when it starts raining for a tire change.
To add to what the others have pointed out about the tires being soft and sticky when hot, many times when a driver runs over debris the debris will actually stick to the tire, sometimes causing problems.
Not entirely true, but the distinction is small. Rain tires (hand-grooved!) are mounted up and distributed at Watkins Glen only for a highly-unlikely set of circumstances:
The rain has stopped.
The track cannot be dried before sundown.
NASCAR decides that they are the only way to finish the race under green.
Never been used, and most teams and drivers have said they wouldn’t use them.
As for dry-weather Goodyear Eagles, I don’t know of a situation where a team would try not changing tires at all (possibly a Busch race at Daytona or Talladega, but I doubt it.) The left sides can last a long while, but the rights are going to give up a lot, and even fresh right sides can make a big difference in lap times.
The pit window at Darlington and Rockingham is usually determined by how long the driver wants to go through the turns sideways at speed.
I saw an episode of Junkyard Wars where three teams had to make oval-track style racing cars. The tires were regular-car style, and you really noticed that the tread cut diminished the footprint area of the tire substantially from the smooth-style used in pro racing.
In fact, they only made it round to the other side of the oval before one guy spun out into another racer and trashed his car.
For the speed-breaks-it-down angle, I recall seeing a show on fast cars where someone had stuck a jet engine on a semi-truck. They shaved regular tires way down for weight, and they only lasted 3 runs or so.
I guess this just means consumer tires are optimized for life rather than performance, so you’ve got an extra reason to laugh at that wannabe peeling out at the lights.
