F1technical.net

Many years ago I was at a drag strip and managed to examine the rear slicks of a dragster right after it had made a run, and it's tires were still hot. When I touched the surface of the tire, it felt like chewed chewing gum, incredibly soft and pliant. I would not have been surprised if some of the compound had stuck to my finger and come off the tire when I removed my hand.

mep wrote:As I flew over the text I recognised that you didn't take
weight balance into account.
The F1 car is only rear wheel driven so lets say 40%
of the force on the driven wheels are lost for acceleration.
Some of it can be recovered by the weight shifting caused by
the acceleration.

Thanks, mep, for reading. You're right, I did not take in account weight transfer in a dragster. I did not think about it, point taken. Friction factors for F1 cars must be corrected and therefore, must be higher that the figures you get if you simply calculate net acceleration. Something like this, for an F1 car that goes from 0 to 100 kph in 2 seconds with a weight distribution of 40% front and 60% rear:

Acceleration = 100km/h / 2sec = 13.8 m/s2 = 1.4 G

Friction coefficient = 1.4 / 60% = 2.3

Which is much larger than the value of 1 assumed by Djones teacher and consistent with the value of 2.2 I got for a dragster.

Anyway, I believe there is no need (in a dragster) to take in account weight balance. The weight transfer must be almost 100%, as this photo shows, so probably the friction coefficient for a drag tire is around 2.2, as I mentioned:



Now that I think about it, weight transfer on a modern dragster is "negative" or "over 100%", meaning that the front tires does not weigh at all, but the "skids" in the back of the dragster do.

The "ideal" run should keep the car as much as possible in a state of balance as the previous photo shows: any weight transferred to those rear skids means less final acceleration.

Besides, you probably need some weight on the front tyres to be able to steer a little your dragster: the larger the steering wheel correction you need to stay on track, the less you can accelerate, if you wish to find the "grip" on the front tyres needed to steer.

Also if your nose is in the air and your arse is stroking the asphalt its not very aerodynamic! This will make a difference to your overall acceleration too as air resistance is squared by speed.

Talking about tyres, whats the best a road legal tyre can menage?

Road legal would mean DOT compliant here in the states. That would include a number of R-Compound tires, like Kumho VictoRacers, or even Hoosier Wet Autocross tires. I wouldn't be surprised to see 1.5g out of these tyres if the car was setup to corner at the maximum (i.e. really stiff, low ride height).

But these R-Compound tires are max treadwear of 50, so you would be hard pressed to get 5000 miles out of these things.

the new audi s6 and bmw m5 both do about 1.2g on factory tyres
edit: checed it up and 1.02 and 0.98 respectively. still its over 1.
tyres are 265/35r19 continental contisport contact 2

How much dose a good go kart develop i mean laterally in the corners ..? I have done lots but i dont feel much ...

I think koenigsegg with Michelin Pilot sport ps2 does 1.3g...
wonder about the Michelin Pilot sport cup

A Kart cannot corner at the limit as well because it has no suspension. This prevents them from getting any negative camber gain during jounce, so the limit of adhesion will be found much sooner. All in all, a kart simply doesn't maximize the potential of the tire, and obviously they are safer because of it.

CMIIW but a kart's frame is designed for controlled flexing, therefore giving some compliance.

On the other hand, surely tyre manufacturers have taken this into consideration when designing their products to ensure max grip, eg. lower inflation pressure? Sidewall design? Just like in F1 where nearly half of the suspension travel is in the sidewalls.

Not familiar with kart tyres so not really sure about that. But I'm quite sure about the frame flexing.

tomislavp4 wrote:I think koenigsegg with Michelin Pilot sport ps2 does 1.3g...
wonder about the Michelin Pilot sport cup

A well setup EvoIX or Evo VIII with Michelin PS or Pirelli PZero Rosso/Zero Corsa can do that, for a tenth of the cost.

Road & Track magazine produced 1.02G lateral grip with the Honda Del Sol - last in production in "97 I believe. Mint they cost aprox' 6K - USD.

the karts that i drove dint have good tyres ..actually it had slicks which were not very nice .. not gripping at all ..... i tried adjusting tyre pressure and all still dint work .... it was rotex karts ... some 32 bhp ....

tomislavp4 wrote:Talking about tyres, whats the best a road legal tyre can menage?

The best any tyre can manage in a road car is the Michelin PAX for the EB16.4 Veyron, theyre very fat and huge, literally...ppl whove driven the Veyron say that it handles like an Elise. Those tyres can withstand 400+kph plus the cornering loads at say 200-250kph..theyre the best for now.

Where did you read that it handles like a elise?

Also those tires do not last long, in fact if you are planning to obtain top speed with the bugatti it is recommended that you get a new set of tires for the run.