F1 tyre sidewall size: Why so large?
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I have wondered, why on earth does F1 cars have so massively large sidewalls?
I know it acts like suspension, and therefore has an effect on the suspension settings of the car, but where does this trend come from?
In DTM, Le Mans, Formula Ford, Formula Renault 2.0 and I could go on, all seem to have medium seize tyre walls. Not large, but not crazy low profile either.
And old F1 cars, like in the 60’s seemed to have a lower profile then the current ones.
It seems like the vast majority of racing series use medium, low profiled tyres, but F1 and a few other open wheel series have gone to very very large profiled tyres. Is it because they act better and bumpers when Maldonardo comes around (yes a Maldonardo joke. Never seen that before have you?), or is it the restriction on rim diameter and a need for larger diameter wheels that has sparked it? In which case, why would you need larger diameter wheels?I assume the superior suspension characteristics are the main reason. The tyre doing all the work allows simpler and stiffer suspension. As far as I’m aware there is no restriction on rim diameter.
But if that was the case then why isn’t it seen in more racing categories? If a F1 car can take advantage from a simple and stiff suspension with a tyre that takes most of the hit, then why wouldn’t it be used in Le Mans, DTM and so on?
It’s what the regulations stipulate.
If I remember correctly, there was a discussion about wheel vs tyre size when Pirelli took over the supplier role, but they didn’t want to change the tyre size drastically, as it would mean that the teams would have to completely redesign their entire car, as the suspension would need to be radically altered (and therefore the chassis, which means the safety cell – all of which will have to pass FIA crash tests again). So they opted to keep the dimensions the same as the old Bridgestones.It’s funny to think that the rim diameter of an F1 car is the same as my mother’s Fiat Panda, perhaps the 2014 regulation changes will be a chance to increase the rim size?
The question behind the thread, IMO, is why the regs stipulate the sidewall dimensions as such, and not why the teams do it. To which I think the answer is sort of along the lines of “if it ain’t broke, don’t fix it.”
In the ‘olden days’ you used to see varying rim sizes on F1 cars as the teams worked with their tyre manufacturers to develop what they thought was the best solution for the car. This was in the days of chunky tyres everywhere in motorsport. The trend for increasingly low profile tyres in sportscar racing really kicked off in the 80s and 90s when they were still using steel brakes with carbon pads, which required huge brake rotors to effectively brake the cars without suffering huge temperature issues. Look at the nineties super touring cars for the best example of this (and if you’re like me, suffer a small pang of nostalgia and lament the sad state of touring cars these days..)
F1 cars adopted exotic brake materials before sportscars and GT racing, so a smaller brake was always a reasonable solution. There’s not really any huge technical advantage to having a high sidewall, other than the inherent suspension characteristics which have their disadvantages as well as advantages. As much as anything else, it’s an aesthetic choice since an F1 car with a low profile tyre would look a bit odd now we’re all used to seeing them with the 13” rims. Obviously since control tyres were introduced, it meant that every car had to have the same sized rims, which in turn standardised a lot of things like damper lengths, wishbone configurations, brake designs, and suchlike (though of course subtle variations are present on every car, depending on their own individual design philosophy).
In order to increase the rim size every car would need to be redesigned for something which would offer virtually no practical benefit other than perhaps reducing the costs of brake materials. Clearly in these days of austerity this doesn’t seem like a particularly attractive solution, though I could see the benefit for the tyre supplier in terms of a greater perception of road-relevance. Perception being the key word here, since clearly an F1 tyre is still going to be an ultra-specialised prototype which would not function correctly on any other type of vehicle.
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