Air pressure adjustments and handling?

Question

i've watched every race there has been (ncts, nns, and nscs) for the past few years, and i'd like to understand the following:

how do different air pressure adjustments to one or more tires affect the handling of a "loose" or "tight" car?

you always hear that some team is taking 1/2 pound out of the right front, or 1/4 pound out of both rear tires, or any of a number of other possibilities.

i know the idea is to affect the handling of the car, but what i don't know is which adjustments to which tires handle which conditions. for example, if the driver is "loose in, tight in the middle, and loose off," what air pressure adjustments might work for that? how about for a driver complaining only of "a tight condition?" how about for "loose, loose, loose" or "need more forward bite?"

color me curious...

Answer 1

My guess would be at least 2 things.

1) A tire with less air pressure would have more grip

2) Tires with different air pressures would have an effect on the "balance" of the car as well.

When a car starts off from a restart the air in the tire may be cold and the pressure may be too low for proper handling. After a few laps the air in the tires heats (hopefully to the proper air pressure) and your car starts to handle better.

If a tire is inflated to normal air pressure at the beginning of a restart then the tire will heat up and build up too much pressure causing the tire to be hard and slide more.

It's all part of the equations.

Answer 2

you start out with low air pressure and as the tires heat up the air pressure go up which will make the car get loose

Answer 3

It's the same as changing springs or moving the track bar or weight jacks. What you're doing is adding or removing weight from a particular wheel. If you are too tight which means you are experiencing understeer, you take weight off the left rear. If you're too loose or have oversteer, you add weight.

You can do little adjustments with the tire pressure so you don't have to spend a lot of time with the jack bolts because you can have the pressures changed before you come into the pits.

Answer 4

It is mind boggling to attempt to commit it all to memory but there is a basic rule . When you decrease air pressure to a single tire it's like making that tire a softer compound increasing the grip on that corner of the car. Lowering the air pressure too far however, will cause the tire to roll over on the sidewall causing that tire to behave as a flat tire does greatly decreasing grip on that corner and making the car squirrely. Ever have a flat or low air pressure on a tire on your car? Same thing but imagine that at 180 mph+. Lowering tire pressure also increases the tire's footprint meaning more rubber meeting the road which translates into more traction. Problem is, if you increase rear traction, you solve the loose condition but can cause a tight condition as the car has more forward bite causing the car to push. AKA slide the front tires. Low pressure can also shorten the life of a tire. Many times the adjustment on one corner will greatly affect the opposite corner. Left rear>right front. right rear>left front. Somtimes they change the airpressure on one corner in an attempt to effect a change on the opposite one. The adjustments made are usually miniscule because the crewchief can never be certain exactly how the adjustment will effect the overall handling. A lot of the time it's trial and error. How many times have you heard a driver say all they did was make it worse or they went too far? Throw all this on top of an ever changing track surface, trac bars, springs, shocks, etc. and  I think it's incredible that these guys ever get a car's handling right. One more thing. Pressure adjustments also effect the roll rate(leaning to the side) of the car similar to a stiffer or softer spring. General rule of thumb. Increased air pressure decreases grip and decreased pressure adds grip. On that corner anyways. I gotta stop now or I'll be running in circles like a dog chasing his tail. I caught mine once. Not a pretty picture. LOL

Answer 5

I've been trying to get a handle on this same topic (no pun intended). I play NASCAR games on the PC and XBOX, and the advanced settings options confound me.  There are so many things that you can do to a car to affect the handling, and every single thing affects something else.  I'm not knowledgeable enough to give you a short, clear, and concise answer, but you may want to check out the following link: http://www.racelinecentral.com/RacingSet... .

If anything, it'll give you an idea of what is going on in general.

Answer 6

Tire with less air, has more grip !!   I know it don't seem like much? But your only using that particular pressure, for about 80 miles or so..

Answer 7

traction and/or grip

Answer 8

Left rear pressure increase will help the car to turn. Front pressure increase will loosen the car up, right rear decrease will free the car in the middle. The the more pressure the harder the tire and the less it will roll over on its side.

Answer 9

tire pressure is used to fine tune the chassis weight jacking on a car.a tire is like a balloon,as the pressure increases the tire "grows" in diameter.i will start in the pits,the tire manager will consult with the tire manufacturer for the proper starting pressure for sidewall roll and growth characteristics and this is called "the base setting".tires are filled with nitrogen instead of compressed air to control the "water vapor expansion"or when air is compressed it has water molecules in it and as the air heats up the water vapor expands at an unpredictable rate causing uneven tire pressures,nitrogen is used because it is compressed from oil vapor and is more stable as heat is introduced and gives predictable pressures.back to pressures and how they effect handling.as the tire pressures increase lets say on the right rear it increases the diameter of the tire to allow the car to "roll"thru the corner.a good example is to get a Styrofoam cup and a coke can and see which one goes in a circle when rolled on its side.the same principle applies to the stock cars tires.this way the driver doesn't have to use as much input into the steering wheel and since stock car racing is basically skid pad and momentum racing even in IRL the less input on the chassis to go around a track the less tire you will use and the less fatigue the driver will incur.

i have been racing since i was twelve years old(i am now 43) i was a tire tester for hoosier tires and also tested tires for goodyear when i raced in Nascar late model series.i am an engineer and chassis designer for late model racing.

Answer 10

hello there,    well i don't know about racing tires & air pressure for any of those circumstances but in driving a car if u have alot of air pressure in your tires it makes the car heavier on the road for driving & the lighter the tires r makes the car lighter on the road for driving.  so that's about all i know about air pressure & i hope i'm right with just those 2 examples too???  i'm pretty sure of it though.  hope i was of some kind of help on your question so good luck with all the different answers u will be getting.  bb