Increased wheel diameter

Does anyone know when the 13" rule came into effect? I took this photo at Silverstone in 1971. These wheels are clearly bigger than 13" with much lower-profile tires than the current ones.
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Currently the tire accounts for 2/3 of the suspension travel. Every suspension would need to be drastically redeveloped, but they pretty much do that every year anyway...

 

The 13" rule was imposed in order to limit brake performance.

 

It's F1, so who knows?..

However, I don't think so - The idea was floated when Pirelli were pissed and thinking about pulling out - you can bet Bernie approached Michelin (among others if the rumors are true), and apparently they said they'd only consider it if they went with 'low profile' tires that were 'more relevant' to their mainstream business.

Now that little issue seems to have been resolved, I can't see it happening. For sure the teams don't want to change - As Craigy noted, the majority of the cars suspension travel (pedantically, their compliance) comes from the tires and changing that would cost serious money..... Damn, they may even have to return to Rose jointed suspension rather than 'flexi' mounts!

I don't think we'll see any changes until there's a new supplier at the earliest.

Cheers,
Ian

 

F1 has to be viable to all demographics.

24 inchers with spinners !

 

I don't want this to happen, the cars are already slow enough

 

This could get interesting.....

While vehicle dynamics, particularly when generating as much D/F as these guys, is a very complex subject, common wisdom (& our own eyes & experience!) suggests 'low profile' tires improve pretty much everything with the exception of 'ride quality', which is hardly #1 on their list......

Cheers,
Ian

 

Michelin was pushing hard to get 18 inch wheels, since there is potentially more
technology transfer to road technology. 13 inch is not relevant. They would gladly
welcome the switch and perhaps they could be interested again in F1.

 

Well for one thing, they would weigh more

 

Err, no.

 

Some info for you:

"It would also create several technical challenges for the team. One tyre manufacturer estimated the increased wheel sizes would add a total of 33kg in weight. That extra weight increases the strain on the gearbox – as A1 Grand Prix discovered when it tried to use a similar tyre specification."

http://www.f1fanatic.co.uk/2010/04/07/why-low-profile-tyres-make-sense-for-f1/

 

What a complete load of bollocks! Whoever that tyre manufacturer is has no clue.... 8kg's heavier per wheel? BS!

Let's look at the current 'best guesses';

- an F1 wheel currently weighs around (probably under) 4kg.
- The current tire weighs ~15kg, a substantial amount of which is in these huge sidewalls of course.

So, for arguments sake, let's say going from 13" to 18" wheels *doubles* the weight to 8kg. It wouldn't, they'd be around 6kg, but I'll be conservative.

"Low profile" tires obviously weigh less - again, being conservative, let's say these things go to 10kg.

You do the math..... Worst case scenario, it's a wash. There's absolutely no way weight would increase by 8kg per corner.

Cheers,
Ian

 

They would slow the cars down.

It is a myth that low profile tyres make cars faster. They don't. All they do is improve steering feel for stodgy rubber steering rack mounted road cars ... F1 cars do not have stodgy poor steering response.

Low profile tyres = less contact patch on the road and that is where cornering grip and performance comes from. With a high profile tyre if your wheel angle changes or you encounter a bump the contact patch is not affected much, but with a low profile tyre it is likely that most of the tyre will leave the ground.

So this is an example of MARKETING instead of performance taking over F1 ... utter crap.

Aussie v8 super cars made the same move to be more relevant with road cars and they had to do a lot of engineering work to make the tyres work. Watch a slow motion video of the tyre flex on these cars during a corner, it is massive. Low profile tyres mean less flex and less contact patch therefore less grip.

Anybody that puts lower profile tyres on their car is a complete dick and has no understanding of vehicle dynamics IMO ... even a Ferrari. Take the 458, the smaller wheel option would lap faster on average over all the possible tracks and road courses ... as everything else is the same, ie. no bigger brakes, etc.

If looks are that important to you, get the big wheels and enjoy some alone time with your hand ...
Pete
ps: sure the engineers will work around this limitation if they go this way but they shouldn't be putting road car based marketing directions on an F1 series. What's next 4 seats?

 

Possibly.... But, they'd figure it out soon enough....

I hear you. [And, FWIW, pretty much agree. ]

Just another challenge for them to overcome - Personally, I'd welcome a return to Rose jointed pick up points etc.

Bwah, bwah, bwah! Typical whining Aussies!

Indeed - Damn things are "bouncing" around all over the shop!

Less flex I'll go with. (Although, I'm sure that could be engineered out if desired.)

Less contact patch? Not so sure - I dunno, but given the same load (weight + D/F) & the same width, seems to me the contact patch would be (pretty much) the same.

Now, when we start bouncing over kerbs, things change, but nothing that couldn't be handled with appropriate suspension design. That they currently get ~1/3-1/2 (?) of their entire suspension movement from the tires doesn't seem "right" to me somehow.

This is one area where I'd like to see some freedom - You can use anything from the current 13"'s thru to 24" spinners as suggested above! Brakes can't be any bigger than they are today.

I asked Rifledriver this Q many years back; "You think you know better than Ferrari the reasons they put those sizes on your car?" was his inimitable response.....

[I stuck with the OEM sizes ]

Cheers,
Ian

 

I recall reading years ago that by lowering the sidewall you stiffen the tire wall and remove its flex from the suspension equation. Suspension movement is easier to control than tire flex and allows for more accurate dynamics. In that current F1 cars get a lot of their suspension flex from the tires a lower profile might be a benefit.

 

That too.....

+1

Cheers,
Ian

 

What difference might there be when it comes to deflation. Would a lower profile allow better control?

 

Ian,

A low profile tyre requires the wheel to be perpendicular to the road all the time to have a good contact patch and that never happens in real life. A higher profile tyre with slightly softer sidewalks can deal with the tyre not been perpendicular without affecting the contact patch.

That is why a sensible but higher profile tyre will result in faster lap times, especially when kerbs are involved.

While I never take Top Gear too seriously the Aussie version proved this. They took a Holden Commodore and did laps with the two different wheel options. The low profile option was 2 seconds a lap slower ... it's for cool looks not performance.
Pete

 

1. That's very anecdotal and hardly scientific.

2. There's a slight difference between a Holden Commodore and an F1 car.

3. Frankly, I don't care if the cars are a bit slower initially. Probably not many here remember 1960-61 when F1 went from 2.5 to 1.5 liters. That was a huge decrease in engine capacity (something I think we could all agree is much more significant than wheel size in terms of overall performance), but within a season or two, other developments led to a net decrease in lap times. That's why I just don't get the whole "OMG, the cars will be slower" schtick.

 

I think what will happen is bigger rims and active suspensions

 

Yes but it is a well known fact. Think about a foot wide tyre with 2 degrees negative camber. The lower profile tyre will have less tyre on the road than the higher profile if the side walls have the same stiffness per square mm. This is because you need the tyre to distort to get the outer area of the foot print down on the road and the higher profile will allow this distortion. The size of that foot print directly relates to the amount of grip.

I don't mind them being slower, but I do not like backward engineering steps. The only reason the tyre manufacturers want this is so the wheels/tyres look more like a road cars ... who cares what they look like.

F1 should not be about looks over function.
Pete

 

Looks are not very important to me either, I just don't think that it has anything to do with "backward engineering steps". As someone pointed out, the 13" wheel diameter was imposed as a way to restrict brake size, which in itself was to limit performance. The tall sidewalls did not evolve as a means to improve performance, but arrived as a way to keep the cars from dragging on the ground with those little wheels.

If, as you state (and your argument does seem plausible; maybe our friend Ian can chime in on that), the taller sidewall flex allows a better contact patch, why do LMP1 cars use wheels and tires that look like this? Okay, maybe it is because Michelin wants it that way for looks and marketing reasons, but if that's the case you still have to admit that they work pretty darned well.

Good discussion here.
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