Generally speaking increasing tire pressures at one end of a car increases the grip at that end. Technically it allows the tires to operate at lower slip angles for a given cornering force. Therefore if you want, say, more oversteer increase the front pressures and/or decrease the rear pressures. Bear in mind these are only general guidelines and, in certain situations, the effect is the opposite of what I just described!
Pressures will also affect mechanical and pneumatic trail, which I totally forgot the concepts about. I think lower pressure = more pneumatic trail, which requires a little more steering effort. I think the tire technicians here can chime in on this.
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I would like if anyone can give some information of what "home made" tests can I perform to get some info/build graphs about tyres.
In my case I need it for improving the track performance and run some simulations of a friend of mine who races in national series (Renault Clio 1.6L NA FWD 220CV 900KG) and the only tire supplier availiable gives us no information. The majority of our rivals use 32/34psi front and 42/44 psi rear (cold tire condition).
I understand that high tire pressure has similar effect of having a stiffer tire construction and stiffer suspension, plus contact patch decreases and rubber has less "intimate" contact with alphalt imperfections, so the overall grip gain is arguable depending on the case. I also understand the limit is the range for the slip angle the tire can handle and this has a lot to do with handling and direction response. I know nothing about the "longitudinal slip angle" and this is something I should learn.
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For road car higher pressure do give you more grip and handling, simply because you have a lot of built-in compliance in the system, with takes huge edge off the response of the vehicle. But they need to meet durability and NVH requirement. I recall a Car & Driver article a few years back testing a Dodge Neon SRT4 on a autoX track for this exact purpose. They run the car at stock recommanded pressure and bumped it up by a whole lot for another run. And the laptime dropped by more than a sec on a 40 something second course.
For race car it might be a different story. And it hugely depends on what tires you run and where it likes to be worked at to extract grip. For our SAE car going from one brand to another the pressure varies 4-5 psi on a tire in that inflates generally between 10-15psi range. And they will both produce the same time around the track(with one being slightly better, which is why we switched)....
Depends. Most tires have a "sweet spot" for tire pressure. Below or above that you'll have grip fall off. Sometimes it's very high, sometimes very low. Depends on the car, how much it weighs, and what kind of tire is on it.
If you run a Corvette tire on a Miata you'd probably have to take a bunch of air out of it.
Best way to find out what's best for your car? Run a DOE. Start at some baseline pressure front and rear.. try maybe +5 and -5 on each axle. See what the difference is in handling.
There can be a big difference in both peak grip and directional stability. Off hand I'd say, if you ran high pressures in the rear, the car might turn well in one direction or the other, but would respond poorly to rapid changes and chicanes.
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ahem...you really can´t give a proper answer on this question.
Generally speaking ,if you don´t really have a clue how to start ,first start with the recommended pressure and work from there .Tyre manufacturers will tell you the correct warm (!) operating pressure for your application .
Basically you would tend to run the lowest safe pressure to maximise tyre grip over a longer period of time.For sure too high pressure will deform the tyre and give less grip,but maybe you need the pressure to keep the tyre in shape due to high speed ,high aero loads.
Some tyres really don´t respond to tyre pressure variations ,basically ,because of their stiff design ,here you might not even notice the tyre beiing totally underinflated,other tyres will show instantly they don´t like underinflation.
Surely it is absolutely mandatory to KNOW exactly the behaviour of the tyre pressure wise .And this is a function of:Driver ,Ambient /Tracktemp,Weatherforecast,Tyre manufacturer,type,Newtyre,used tyre,Setup of car,Geometric issues with the car ,corner weights,amount of downforce,number of laps to be covered.....to name some variables.
At the end of the day tyre pressure is NOT the big question ,it is performance.
So the question is :what can I do to maximise grip laterally and longitudinally,do
I need this for one lap or the whole damn 50 laps.
As you see this is where experience and structured methodical approach combine to
unfair advantages.Taking and monitoring pressures and temps every time the car leaves and enters the pits is a bloody elaborate job but it definitevely helps .
greggy_thommo wrote:What is the effect of tyre pressure on handling, and what are the average pressure ranges teams run for various sets of tyres and conditions?
As an example, if you were to have the front tyres very low pressure and the rears very high pressure, would the car oversteer?
I'm just looking for a general concept of how tyre pressures are used to set up a car.
More intelligent posters than me have answered with a resounding . . . "it depends."
I'd just like to add that once you do get your suspension settings AND tire pressures into an effective range, varying pressure by as little as a pound (or even less?) can make a noticeable difference. Perhaps one of our NASCAR followers can comment here, because I've noticed TV commentators discussing this trait during NASCAR races.
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