Low profile tyres vs F1 tyres

Low profile tyres vs F1 tyres

Author
Discussion

wadgebeast

Original Poster:

3,856 posts

171 months

Wednesday 23rd January 2008
quotequote all
Random question that occurred to me last night...

If low profile tyres improve grip and handling at the expense of comfort (small tyre wall flexs less), why do the tyres on F1 grand prix cars look so tall? Is it because the wheels are so small in order to save weight, so the tyres need to be taller to give sufficient ground clearance? F1 tyres are designed for one job and one job only, so I'm guessing the sidewalls can take the strain.

Any thoughts / definitive answers?

The Hitman

2,584 posts

170 months

Wednesday 23rd January 2008
quotequote all
Smaller Tyres = Less Rubber = More Travel = More Wear

Mr E

19,468 posts

219 months

Wednesday 23rd January 2008
quotequote all
Half the suspension movement of an F1 car is in the tyres.

chrisr29

1,216 posts

157 months

Wednesday 23rd January 2008
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Mr E said:
Half the suspension movement of an F1 car is in the tyres.
You sure? How come they don't flex like mad under cornering load? If a road tyre of that profile was subjected to that sort of cornering load it would roll off of the rim.

tvrbob

10,800 posts

215 months

Wednesday 23rd January 2008
quotequote all
Low profile = better handling? Quite the opposite actually.

Low profile is often better on a very smooth surface like a track but on the road the lower the profile the greater the level of bump steer, tramlining and any under or over steer will be increasingly violent. Tyres need to flex sideways and up & down to absorb irregularities in the road. Low profile is a max power thing.

The question about F1 cars I can't answer, I don't know why.

10 Pence Short

32,880 posts

177 months

Wednesday 23rd January 2008
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As far as I'm aware the regulations determine wheel size.

With that size wheel the best profile is the one you see on today's cars. The idea is that the tyre acts as a large proportion of the suspension movement allowing the car to be as stiff as possible.

As for them moving about a hell of a lot, take a look at the slow mo replays when the cars travel over the kerbs!!


Max_Torque

15,858 posts

177 months

Wednesday 23rd January 2008
quotequote all
Tyre profile is actually a result of the wheel diameter required to fit big enough brakes and suitable suspension geometery within an overall wheel and tyre size.

F1 cars have carbon carbon brakes that are small and suspension geometery design for smooth roads and low total travel, hence they can have small wheels, which are also tightly controlled in the regs.


Mainly, for road cars, someone has decided that big wheels look better than small wheels!

flemke

22,618 posts

197 months

Wednesday 23rd January 2008
quotequote all
Formula One cars are not allowed to have wheels bigger than 13" diameter. It's been this way for decades.The F1 designers try to make the best of a bad situation by utilising the tyre as a springing medium. The actual springs on an F1 car have virtually no travel.
If you want to see what they would run if there were no limit, look at LMPs, IRL, etc.

kambites

60,293 posts

181 months

Wednesday 23rd January 2008
quotequote all
Even the Le Mans prototypes don't have particularly low profile tyres though. Nowhere near as low as a lot of road cars.

ETA:


Edited by kambites on Wednesday 23 January 12:46

Fume Troll

4,389 posts

172 months

Wednesday 23rd January 2008
quotequote all
wadgebeast said:
Random question that occurred to me last night...

If low profile tyres improve grip and handling at the expense of comfort (small tyre wall flexs less), why do the tyres on F1 grand prix cars look so tall? Is it because the wheels are so small in order to save weight, so the tyres need to be taller to give sufficient ground clearance? F1 tyres are designed for one job and one job only, so I'm guessing the sidewalls can take the strain.

Any thoughts / definitive answers?
Remember, F1 cars are built to a formula, rules which can limit performance. They don't necessarily use the best of anything, or use a given technology to its best advantage.

Cheers,

FT.

rev-erend

20,648 posts

244 months

Wednesday 23rd January 2008
quotequote all
Big wheels are heavy ..

I weighed my TVR wheels and tyres

235/35 18 inch = 22kg

225/50 15 inch = 17.5 kg

That's a lot of unsprung weight .. no one wants that in F1 I would guess.

It's only the customer and marketing departments that want 18/19 and 20 inch wheels..

LeoSayer

6,129 posts

204 months

Wednesday 23rd January 2008
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I've experimented with different size wheels and tyres on my Porsche and Audi and lower profile tyres offer nothing except better looks.

Ride = Less comfort
Tyres = More expensive
Grip = no difference
Handling = no better or worse
Acceleration and braking = no difference

cptsideways

13,144 posts

212 months

Wednesday 23rd January 2008
quotequote all
I'm pretty sure a higher profile tyre dissapates heat better than a low profile one with a bigger wheels.

Low profile tyres on road cars is just a fashion thing

flemke

22,618 posts

197 months

Wednesday 23rd January 2008
quotequote all
kambites said:
Even the Le Mans prototypes don't have particularly low profile tyres though. Nowhere near as low as a lot of road cars.

ETA:
I think you'll find that those are 18" wheels - quite a bit bigger than 13".

Certainly it is true that the 20 and 25 aspect ratios that are used on some road cars are chosen for looks, which is a bit ironic, considering that they usually look ridiculous.

Fume Troll

4,389 posts

172 months

Wednesday 23rd January 2008
quotequote all
I suppose that up to a point the main (non-cosmetic) point of larger wheels is the ability to fit larger brake rotors. I would guess there is a limit to the size of rotors F1 cars are allowed.

Cheers,

FT.

lance1a

1,337 posts

158 months

Wednesday 23rd January 2008
quotequote all
F1 tyres are fairly low profile when you take the width into consideration anyway. I suppose a lot to do with the weight and absorbtion qualities...weight of alloy VS rubber-weight of rubber VS suspension components. Have you ever picked up an F1 wheel/tyre combo? I did and it was so light I thought it was fake!

flemke

22,618 posts

197 months

Wednesday 23rd January 2008
quotequote all
rev-erend said:
Big wheels are heavy ..

I weighed my TVR wheels and tyres

235/35 18 inch = 22kg

225/50 15 inch = 17.5 kg

That's a lot of unsprung weight .. no one wants that in F1 I would guess.

It's only the customer and marketing departments that want 18/19 and 20 inch wheels..
For the same rolling circumference, you'll lose a lot of control by adding 1 1/2" to the sidewall height. To compensate, you can have a stiffer construction, but that's putting weight back on again.
I wouldn't know about the particular wheels that you have weighed, as there are a number of variables. The farther out it is from the axle, the worse any extra weight will be. The bulk of the weight in a wheel is towards the centre, as the material is under the greatest force near the junction of the spoke and the centre. This partially mitigates the drawback of a wheel's being heavier because it is a bigger diameter.
Also, by increasing wheel radius we decrease sidewall height, so there is something of a weight reduction achieved there.

The Walrus

1,852 posts

165 months

Wednesday 23rd January 2008
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The profile on road cars is very much marketing IMO I actually prefer the handling of my car on 16's than 18's it is much more compliant and adjusable on the limit, EVO's test on tyres highlighted this finding that the 17 inch wheel with a 225/45 aspect ration was far better than that of the 18 x 225/40 tyres.

You may also find when you look at the large majority of supercars the height of the sidewall on say a 19x315x25 is big compared to an 18x225x40 tyre as it is a % not a specific height if that makes sense. So sometimes low profile is not really accurate.

Anyway the LMS cars tyres will normally have big sidewalls to allow for extra tread and wear rates associated with endurance racing. also have a look at some external vids of touring cars from the mid to late 90's and you will see why low profile is not great in racing, in some cases you will see metal touching tarmac due to the tyre wall not have enough compliancy or area to cover the wheel under hard cornering.

JR

12,180 posts

218 months

Wednesday 23rd January 2008
quotequote all
flemke said:
Formula One cars are not allowed to have wheels bigger than 13" diameter. It's been this way for decades.The F1 designers try to make the best of a bad situation by utilising the tyre as a springing medium. The actual springs on an F1 car have virtually no travel.
If you want to see what they would run if there were no limit, look at LMPs, IRL, etc.
Yep, since about 1970.

flemke

22,618 posts

197 months

Wednesday 23rd January 2008
quotequote all
The Walrus said:
Anyway the LMS cars tyres will normally have big sidewalls to allow for extra tread and wear rates associated with endurance racing.
scratchchin
How much tread wear do you think there is?
I've never measured it, but I'd be surprised if there were more than 3.5 mm of designed wear on a slick. Even wets, which have extra-deep blocks to shift water and also to generate tyre temp, have no more than 7 mm.
The tread on a slick cannot be very thick, or it would overheat.