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So, with the current 13inch tyres having most of the suspension travel contained to the sidewall of the tyre itself, would a move to 18inch low-profile tyres force the teams to give up their current aero-centric designs to maximize mechanical control, and would that be a beneficial reduction of aero that may close the gaps between the teams?

Please discuss.

18 inch wheels with active suspension. Perfect?

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JonoNic wrote: ↑

17 Apr 2018, 20:26

18 inch wheels with active suspension. Perfect?

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I like the idea of active suspension less than the current setup. The simplicity that the teams currently express the super complicated suspension control with is an engineering marvel in my eyes. Active (or reactive as most likely) takes away a large component of car setup, and I think that is a big part of the up and down swings thru out the season, and I'd hate to lose the nail-biting drama that comes with it!

Zynerji wrote: ↑

17 Apr 2018, 20:19

So, with the current 13inch tyres having most of the suspension travel contained to the sidewall of the tyre itself, would a move to 18inch low-profile tyres force the teams to give up their current aero-centric designs to maximize mechanical control, and would that be a beneficial reduction of aero that may close the gaps between the teams?

Please discuss.

I wouldn't think so, no.

For one, this is very difficult to have any sort of definitive case made because it's all hand waving and speculation. Furthermore, going from a 13 to 18 inch rim diameter may have non-trivial effects in and of itself with any flow that comes through them, or subsequent downstream wake. I'm not an aero guy, I don't know.

Ultimately, ride rate is important. Let's assume that it's correct that the largest contributor to sprung platform travel is indeed the tire's deflection. If so, don't forget - that's by choice.

Let's assume with a 13 inch rim tire, the tire has spring rate X1. For whatever reason - I want body heave rate Y, let's say it's what I believe is the best balance of mechanical grip and aero platform control. To accomplish this, I need wheel rate (i.e. from main springs) Z1.

If now I have a different rim diameter tire, maybe it has spring rate X2 > X1. To maintain the same body heave rate Y, I now choose wheel rate Z2 < Z1, e.g. softer chassis main springs. It's like you're trying to maintain the same overall vehicle response, you just proportion it differently through the system.

Ultimately, if your goal is closer parity between teams and organizations, I don't think rim diameter has any bearing on it.

Zynerji wrote: ↑

17 Apr 2018, 20:19

So, with the current 13inch tyres having most of the suspension travel contained to the sidewall of the tyre itself...

Do they though? Not that I disagree that sidewall height is a massive influence, but this image always amazes me…

I think there's another similar topic somewhere in the ether, but, from an aerodynamicists perspective having less compliance in the tyre side wall is a benefit. A lot of the issues teams have with CFD--wind tunnel--track is about accurately modelling the tyre behaviour. If the side wall moves less then you have a more predictable system, which can only be a good thing. There are other issues, like the shape of the side wall - which is much squarer with an 18" wheel. That's a workable issue though.

However, you don't want a tyre which is too stiff so increasing the wheel diameter from 13" to 18" would also likely come with an increased tyre diameter. Where F1 dry tyres are currently 670mm in diameter, so the side wall depth is 169mm, the Michelins Formula E use are Fr: 24/68-18 x 275mm, Re: 27/68-18 x 305mm, while LMP use the same size front and rear - 31/71-18 x 14" (355mm). That's a side wall somewhere between 111mm and 126mm. Using that same notation the F1 dry tyres are - Fr: 30/67-13 x 370-385mm, Re: 40/67-13 x 455-470mm, which gives an example of just how unnecessarily massive F1 wheels are!

Assuming an increase in diameter, if F1 were to keep the same tread width the wheels would get a bit narrower because of the squarer profile, so Fr: 30/71-18 x 345mm and Re: 40/71-18 x 445mm... which is still massive, but is a saving on frontal area, which is again beneficial. I'd be in favour of then dropping the tread and wheel width closer to the Le Mans tyres/wheels because of the issue of unsprung mass with such huge wheels. I think an F1 rear wheel/tyre is already pushing 20kg, LMP limits the wheel to a minimum 7.5kg - so probably ~10kg with the tyre.

So less frontal area and a more predictable side wall I'd say is a net benefit for aero, but the wheel widths would probably have to be reduced.

formula-e tires look terrible

BrunoH wrote: ↑

18 Apr 2018, 19:21

formula-e tires look terrible

In what way? The dimensions or the "all weather" tread pattern?

Zynerji wrote: ↑

17 Apr 2018, 20:19

So, with the current 13inch tyres having most of the suspension travel contained to the sidewall of the tyre itself....

Fogive me Zynerji, but I'm not sure I agree with that assumption. I have listed a few results obtained from multi-post rig tests below.

The numbers represent the fraction of body travel caused by the tyres at 5 Hz. The input was a sinewave in heave, and the results were taken for "customer" suspension set-ups, Front axle followed by Rear axle. "Road" results were for a "high end" road car.

F1........0.598....0.402
FE........0.364....0.409
Road...0.265....0.398

jjn9128 wrote: ↑

18 Apr 2018, 15:08

think an F1 rear wheel/tyre is already pushing 20kg,

Not even close, half that.

PhillipM wrote: ↑

18 Apr 2018, 23:17

Not even close, half that.

Yeah I thought that, but the halo tests all quote a wheel weight of 20kg... maybe they were weighted to assume brakes...etc Thinking about it, that's probably where I got confused...

Zynerji wrote: ↑

17 Apr 2018, 20:19

So, with the current 13inch tyres having most of the suspension travel contained to the sidewall of the tyre itself, would a move to 18inch low-profile tyres force the teams to give up their current aero-centric designs to maximize mechanical control, and would that be a beneficial reduction of aero that may close the gaps between the teams?

Please discuss.

looking at this proposal purely from a function of the tyre as what is considered as suspension may overlook road compliance that tyres provide by absorbtion.
if F1 were to change to lower profile I think they may be very difficult to drive without major suspension redesign that may compromise what exists.
in other words tyres provide a very effective part of driveability distinct from suspension, sort of why they were invented in the first place
from 'not the chassis guy'

jjn9128 wrote: ↑

18 Apr 2018, 23:32

PhillipM wrote: ↑

18 Apr 2018, 23:17

Not even close, half that.

Yeah I thought that, but the halo tests all quote a wheel weight of 20kg... maybe they were weighted to assume brakes...etc Thinking about it, that's probably where I got confused...

The guy martin show where he joined the Williams pit crew talked about 19kg for a rear wheel with tyre. so +1

mrluke wrote: ↑

19 Apr 2018, 00:29

The guy martin show where he joined the Williams pit crew talked about 19kg for a rear wheel with tyre. so +1

That was on the other day. Now that you mention it I can recall the scene. Who knows any more

jjn9128 wrote: ↑

18 Apr 2018, 20:21

BrunoH wrote: ↑

18 Apr 2018, 19:21

formula-e tires look terrible

In what way? The dimensions or the "all weather" tread pattern?

haa it looks odd, i mean its like a big rim but low profile tire.. looks too street and not that race were used to? if you know what i mean?

i think if they went from 13 to 14 or there abouts it wold be ok.. but not more than that...