Tires

[Liz]

When Gil de Ferran ran on Goodyears it was conceded by everyone but possibly him that this was a serious handicap, and from what I understood - and it wasn't much - this was mainly because the Goodyears took such a long time to come up to temperature - frequently causing the Walker car to slew into the wall on restarts or spin on parade laps, etc. Memo Gidley, after his stint at Walker on Goodyears, said that driving on Firestones on his next "Sub" job made all the difference in the world to what he was able to do in the car.

Why was there such a massive difference between Goodyears and Firestones and why could Goodyear never get it right?

[enzo]

Tire design is still a bit of a black art, and findng the next bit of magic is often due to sheer luck.

Tire compounding is an unbelievably complex process, with a ton of variables that still aren't fully understood. Rubber is made up of a lot of different things, with each component adding it's own unique flavor to how the tire will behave. Add just a 1% more or less of a particular component, and you'll get an entirely different tire.

Of those different components, many are synthetic oils or solvents. Sometimes, by sheer luck, a company will find that a particular oil, when added n a particular quantity, and when combined with very specifc quantities of other specific components, with produce characteristics that no other combination of things will emulate. Sometimes that one magical component is produced by only one company in the world, and only in small quantities, or even only as a waste by-product of another process.

Most likely, Bridgestone found one of those magical components, and that's all it took to get the edge over Goodyear.

Years ago, Firestone came up with a tire compound that was pure magic, and dominated the amateur FF scene for that year. The next year they were out to lunch. The problem was that the refinery that produced a particular oil used in that compound burned to the ground, and there was no other source anywhere in the world. Firestone tried everything they could think of to replace that oil, but nothing else even came close. It wouldn't surprise me if Bridgestone reserected the production of that oil and is using it now with the same results.

[Tris]

Hi all!

This is my first post to the technical forum so please bear with me as my knowledge is woeful!

While I agree that tyre compounds are important there are many other factors to consider in tyre performance... or so I understand ?!?1 (If I am wrong please correct me)

1.) Contact Patch.
This is the area of the tyre that is in contact with the ground. This area has to be of sufficient size in relation to the vertical and lateral loading for the preface of the car. The correct term is traction but the term used in motor sport is grip. The size of the contact patch (bigger the contact patch the more “grip” available) is important when the car is accelerating in a straight line too even though there is no lateral loading. If you think of dragsters they are rear wheel drive and have massive rear tyres. this allows for a large contact patch so the engine can have more of the power working more of the time. The wider the tyre the larger the contact patch.

2.) Slip angle
When a car is cornering the manner in which the tyre resists the central fugal (G Force) force is using a mixture of a flexing and scrubbing action. Under centrifugal loading each contact patch progresses along the tack surface at an angle to the plane of the wheel... this is called the slip angle. The amount of slip angle is determined by the size of the tyre, it’s compound, inflation and amount of aerodynamic force exerted on the tyre. The slip angle is vital to race car design. It is used is used extensively in the analysis of race car aerodynamics and cornering ability.

3.)Camber Thrust
The cornering power (grip) of a tyre can vary significantly with the wheel camber angle relative to the surface of the track as governed by the movement of the chassis. When a car is set up statically is set-up with a small amount of negative camber according to the expected chassis role in cornering so that in cornering the camber angle (the angle made between the bottom of the tyre and track) is O degrees. this is the optimum as you get the largest possible tyre contact patch. The camber is largely responsible for keeping the contact patch as large as possible. The camber can be controlled by altering the settings of the anti role bars and the spring... i.e. controlling the amount of chassis role.

4.)Construction.
The construction of the tyre is responsible for the amount of flex that the tyre has. I believe that most racing tyres are of the radial type.

5.)Compound
The tyre are made from a huge number of different chemicals. The polymers used have to have good resistance to abrasion and good properties with regards to absorbing energy (think like a running shoe) I know the they add zinc oxide, certain waxes, oils and oil derivatives. Different tyres have different compounds and different constructions to give them different characteristics. The softer tyres have more oil in them than the harder tyres and this means that there is less “space“ for the chemicals that give the tyre resistance to wear.. The grip is produced by a molecular interaction between the tyre and the track surface.

6.)Pressure
The pressure of the tyre determines the co-efficient of friction of the tyre, i.e. how much horizontal load the tyre requires to make it slip. The higher the pressure in the tyre the harder it is and the less it is able to absorb the bumps on the track and the car bounces and thus it is not in contact with the track. The lower the pressure the more the tyre flexes and more heat is produced and thus it is harder to get the tyre to work at the optimum temperature.

7.)Tread.
If the car has grooved as opposed to totally slick tyres (like current F1 dry tyres) the tyre “squirms” more. This is the flexing of the tread as opposed to the flex of the tyre. This means that the tyre generates more heat and is harder to keep at the optimal temperature. Apart from the smaller contact patch accounting for more wear this is why the grooved tyres have to be harder than the “old style” slick dry tyres. Wet tyres can be softer than the dry tyres. This is because they have to work in cooler temperatures as they are cooled by the surface water on the track.

8.)Stagger.
Stagger in the term used to described the difference in diameter between the left and right and side of the car that causes imbalance between left and right hand cornering. tyre stagger is used to aid cornering on ovals in Indycar to aid cornering in the direction of the oval. In F1 tyre stagger happens as a result of inaccuracies in manufacture (the smaller the tyre in relation to the bead that hold it to the rim the more accurate the tyre. although some drivers prefer some stagger on the rear tyres. Stagger is easy to unbalance a Formula One car as any difference in tyre diameter upsets the static cornering weight and transfers the main weight when the power is applied. Actually some handling problems can be cured by swapping the left and right hand side tyres. That is why the teams specify which tyres are on the right and left hand side.. look at the tyre warmers at the pit stop.