Low profile and High Profile tyres

[midzt]

This is probably pretty basic, and tbh I'm pretty sure that it is, but why do F1 cars use such high profile tyres, whereas other race series such as Touring Cars, and sports cars in general, use low profile tyres?
Is it just due to the G's that F1 cars can pull in corners, and need higher side wall strength so the tyres don't fail? or am i completely wrong.

Thanks for any replies, just a little intrigued.

[rkn]

Because suspensions today are so stiff to ensure a stable aerodynamic platform, so the tyres have to take care of a lot the damping

[Sawtooth-spike]

i thought it was because the rules said they had to be of a set size

[kilcoo316]

i thought it was because the rules said they had to be of a set size

Yeap.


The teams would like smaller sidewalls, but the rules prohibit it. There was an article by mike gascoyne in racetech on it a few years back.

[midzt]

I see, so what actually are the advantages of a low profile tyre? I would have thought only the rolling radius would matter? And how come the FIA have prohibited them?

[Ciro Pabón]

I'm not sure, as always. But even if lower sidewalls would improve your handling, because the tyre won't "twist" or "bend" so easily in an important way (probably proportional to the cube of the wall length), the tires have another use: they cushion the car (and the poor driver, that doesn't get too much cushioning from the hard F1 suspension). Higher walls should mean higher cushioning, unless I'm mistaken.

Why this is the proper balance for F1 and not for other series, it's a mistery to me.

[RH1300S]

If the rules allowed - a low profile tyre would let you run bigger brake discs for a given rolling radius.

I won't give you BS about stiffer sidewalls etc. - I'd just be guessing! But at a GUESS it's probably easier to control the sidewall flex. Certainly if you drive a car with low profiles they feel more direct (also tend to break away more suddenly).

I am pretty sure that the low profile tyre weighs less (less of it - so surely?) - and the extra wheel does not weigh that much more. So you have benefits with unsprung weight and intertia.

Having low profiles has to be an advantage with the suspension design. At the moment some of the car's spring is in the tyre (probably much more than they would like). They don't have much control over it's rate or damping. Putting low profiles on must give back some control of the car's springing and damping to the stuff in the chassis that was actually designed for the job in the first place.

[BreezyRacer]

While low profile tires would most likely provide a handling benefit they do suffer in one important way .. their lack of ability to store torque windup makes them easy to spin under throttle. Hence, if allowed F1 teams and tire mfrs would likely use low profile tires on the front but maintain tall sidewalls on the rear.

But tire mfrs are working hard within the rules so it's hard to say if there would be definiative improvement. If you look at how little deflection there actually is under the extreme cornering loads of F1 you have to deduce that F1's tires are massively stiff. Just look at how closely builders would place bodywork to tires if allowed (there is pretty large free space that is regulated around tire areas now). When that area was unregulated a few years ago some teams had bodywork maybe within 20 mm of the sidewalls.

I've got some pics of cars going thru Aue Rouge which has not only extreme cornering loads but also vertical loads and the tire deflection there is nil, maybe 10-15 mm if I had to guess from the pics. Amazing!

As a bit of a comparitive, on my little race car I get over 50 mm of tire deflection that I have to allow for .. and I'm only pulling about 1.5 g's.

[kilcoo316]

Renault introduced the mass damper largely as a result of the tyre's damping characteristics.


If the teams feel the need for the damper - they obviously aren't 100% with the tyre under dynamic loading/unloading.

[BreezyRacer]

Renault introduced the mass damper largely as a result of the tyre's damping characteristics.
If the teams feel the need for the damper - they obviously aren't 100% with the tyre under dynamic loading/unloading.

I thought the mass dampener was for dampening ballast which was ballasted out in front of the chassis?

[kilcoo316]

I thought the mass dampener was for dampening ballast which was ballasted out in front of the chassis?

No, the mass damper was ballast, that was used to counter-act the natural frequency of the tyre osscillations.

It kept the car much more stable, and that allowed more agressive aerodynamic configurations - which is the loophole the FIA used to ban it.

[joseff]

F1 tires *are* low profile (IIRC 30 or 35 at the back) they're just so wide that the 30% translates into tall sidewalls.

[BreezyRacer]

In contrast to other forms of racing such as LeMans, they are not. According to an old book I have written in the 70's anything under a 70 series tire is "low profile". Times change and today's race tires and lots of street tires are much lower profile than today's F1 cars.