13 replies to this topic

[rodders47]

Can some one more wiser then myself explain to me WHY Low Profile tyres (like those used on high priced sports cars sold to Joe Blow Public) are not used in F1 or for that matter most of the top racing categories?

Maybe it is because of the suspension, or lack of, but if it's good enough for road cars why not for Race cars?

[Jean Todt]

rodders47, on Aug 14 2007, 06:39 AM, said:

Can some one more wiser then myself explain to me WHY Low Profile tyres (like those used on high priced sports cars sold to Joe Blow Public) are not used in F1 or for that matter most of the top racing categories?

Maybe it is because of the suspension, or lack of, but if it's good enough for road cars why not for Race cars?

Yes, F1 cars dont need Low profile tyres, Mainly due the placement of the suspensions, which takes most of the force sidewise, a reason why they are so sensitive. Low profile tyres will make it very uncomfortable to drive.

A lot of higher racing series infact do use low profile tyres, but with different compounds. Those tyres dont need to last thousands of Kilometers so, in order to squeeze grip they need to wear out faster of better adhesion.

If WRC is considered to be a racing category, even they use low profile tyres in some stages, but different suspensions and Damping set ups.

[rodders47]

abbas_gear, on Aug 14 2007, 06:55 AM, said:

Yes, F1 cars dont need Low profile tyres, Mainly due the placement of the suspensions, which takes most of the force sidewise, a reason why they are so sensitive. Low profile tyres will make it very uncomfortable to drive.

A lot of higher racing series infact do use low profile tyres, but with different compounds. Those tyres dont need to last thousands of Kilometers so, in order to squeeze grip they need to wear out faster of better adhesion.

If WRC is considered to be a racing category, even they use low profile tyres in some stages, but different suspensions and Damping set ups.

I can accept your answer there for the reasons stated, But I have always been of the belief that Motor Racing Developments filtered down to the ROAD CAR, but as far as these low profile Tyres it seems not to be the case, that is why I asked the question WHY.

And given that the low profile tyre/wheeel assembly would be a lot less in the "Unsprung Weight" that for so many years when I was involved on the mechanical side of motor sport was the Holey Grail that was the way to go in Race cars, I wonder why this has not been accept in F1

[LabradoRacer]

Low profile tyres? What are they? Tyres which aren't advertised much?

[scarbs]

F1 cars would use low profile tyres if they were allowed.  But the rules demand 13” diameter wheels.  This is an old rule, originally kept to prevent teams fitting ever larger brake discs.  The FIA have stated they would like to go to lower profile tyres, but this doesn’t appear to been added to the rules proposed for 2008-2009 or 2011.  
As F1 Cars use tall such tyres, a large proportion of the cars movement is made up from the tyre (about 80-90% of the movement).  This is actually undesirable nowadays as the tyres spring and damping cannot be tuned, as it could if the movement came from conventional suspension.  Last year Renault tried to offset this uncontrolled movement with the Tuned Mass Damper.  
Also the tall tyres create a lot of slip. Which is the tyre twisting around the contact patch, so that the direction the wheel is turned in is offset from the actual direction the tyre is pointed in.  this affects turn in and again would be dialled out if possible.

Scarbs

[rumblestrip]

Good question rodders!    It's something I never really though of before now.

[duest]

And can someone explain why they cost so damn much?! I'm guessing it is to do with their construction.

LabradoRacer, on Aug 16 2007, 05:16 PM, said:

Low profile tyres? What are they? Tyres which aren't advertised much?

The profile refers to the tyre's sidewall height vs tread width. So the smaller the height is vs the width the lower the profile is.

[Jean Todt]

LabradoRacer, on Aug 16 2007, 07:46 AM, said:

Low profile tyres? What are they? Tyres which aren't advertised much?

its usually referred as High performance tyres.

[Jean Todt]

duest, on Aug 16 2007, 01:45 PM, said:

And can someone explain why they cost so damn much?! I'm guessing it is to do with their construction.
The profile refers to the tyre's sidewall height vs tread width. So the smaller the height is vs the width the lower the profile is.

First of all, its because of the lower production, and yep, construction or compound.

[rodders47]

what I meant by "Low Profile Tyres" is: I suspect the tyres used in F1 would be about 30% profile, where as my normal road car uses 60% profile, but if you look at some of the high performance normal road cars here in OZ the tyre profile looks like maybe 80% or more, actually the tyre looks like a large rubber band on the rim!!

I can accept the 13" rim diameter so as to control the Brake Diameter, but that can be controlled regardless of the rim Diameter.

My main reason for asking this is that I feel F1 are using the "Flexibility" of the larger profile tyres to provide suspension performance, at the expense of that "Un Sprung Weight" that when I was racing was the most crucial part of car setup

[Jean Todt]

rodders47, on Aug 21 2007, 06:35 AM, said:

what I meant by "Low Profile Tyres" is: I suspect the tyres used in F1 would be about 30% profile, where as my normal road car uses 60% profile, but if you look at some of the high performance normal road cars here in OZ the tyre profile looks like maybe 80% or more, actually the tyre looks like a large rubber band on the rim!!

I can accept the 13" rim diameter so as to control the Brake Diameter, but that can be controlled regardless of the rim Diameter.

My main reason for asking this is that I feel F1 are using the "Flexibility" of the larger profile tyres to provide suspension performance, at the expense of that "Un Sprung Weight" that when I was racing was the most crucial part of car setup

There may be more reason for an F1 car to use such profile, but, it is the tyre that is the main part of the suspension, since it is the tyre that goes through every bit of abuse before any other part of the car goes through. F1 cars need higher profile tyres to absorb the shocks and force since its suspension/shockabsorbers are placed to absorb force from sideways inorder to increase cornering speeds and stability compared to the shockabsorbers found on a normal car, where the basic requirement of the suspension is for comfort.

[mikathegreat2]

Low-profile tyres are wide but very skinny & are usually on cars with big 1 inch wheels! F1 tyres need big, fat & chunky long-lasting tyres!

[rodders47]

maybe I never explained what I was trying to say here very clearly?

In all the years of my involvement in motor racing THE most important thing that everyone tried to ELIMINATE was "Unsprung Weight" i.e. the weight of any part of a car that was Not affected by the springs and that is wheels /hubs/tyres etc.

The current F1 wheels are 13 " diameter, but the tyres are Much bigger in diameter, thus the weight of the tyre would have been ,in my days of racing, of concern because of the tyre's weight.

The current "low Profile" or very small diameter of the tyre (an 18" rim fitted with a low profile tyre measures about 26" max. in Diameter) would mean a lot less unsprung weight. The tyre will still last the distance, as I percieve that is the compound used that will make it last the distance, BUT there is less damping in a low profile tyre, and also less sidewall movement, which we all know creates heat build up in the tyre.

Also due to the lower profile there is less chance of the sidewall being punctured.

Just would like a real technical reason why they are not used in F1 as it does amase me somewhat.

[Jez]

rodders47, on Aug 25 2007, 04:57 PM, said:

maybe I never explained what I was trying to say here very clearly?

In all the years of my involvement in motor racing THE most important thing that everyone tried to ELIMINATE was "Unsprung Weight" i.e. the weight of any part of a car that was Not affected by the springs and that is wheels /hubs/tyres etc.

The current F1 wheels are 13 " diameter, but the tyres are Much bigger in diameter, thus the weight of the tyre would have been ,in my days of racing, of concern because of the tyre's weight.

The current "low Profile" or very small diameter of the tyre (an 18" rim fitted with a low profile tyre measures about 26" max. in Diameter) would mean a lot less unsprung weight. The tyre will still last the distance, as I percieve that is the compound used that will make it last the distance, BUT there is less damping in a low profile tyre, and also less sidewall movement, which we all know creates heat build up in the tyre.

Also due to the lower profile there is less chance of the sidewall being punctured.

Just would like a real technical reason why they are not used in F1 as it does amase me somewhat.

Maybe that's your answer there