67 replies to this topic

[Wolf]

I'd like to think it was the impractical nature of slicks that put them off (hopefuly, they weren't do blind not to consider the idea)... I mean, what chances does one have of returning to pits (with the car in one piece) if rain caught him in Hatzenbach on the 'Ring? And at Spa- say, it hasn't rained in a while and all the oil and muck float to the surface when the rain starts, and one say approaches Masta in full flight. I think safer cars and modern Mickey Mouse circuits certainly helped the idea of using tyres dedicated solely to fair wheather conditions...

[A E Anderson]

Originally posted by Mike Lawrence
I have never understood why it took mainstrem motor racing so long to latch on to slick tyres. I was racing karts in 1961 and we used slicks. A company called Blue Peter did remoulds and we sent away our knackered knobblies, together with £1. 10s (£1.50) per tyre they came back as slicks.

The Americans were on to the idea before we were, and slicks had long used in drag racing, why did it take so long for everyone else to catch on?

Slicks came into use by the early 50's in midget racing, as paved tracks became more popular. The idea probably came from the early drag-racing crowd, who discovered that a tire, with the tread worn smooth, actually got more grip than one with any tread pattern to it. Firestone, then the only race tire manufacturer in the US, began offering both Midget slicks for oval use (highly offset, with a built-up shoulder on what would be the right side of the tire, and the left side being curved a bit into the sidewall. Someplace in my collection of reference works, I have a Firestone racing tire catalog from 1958, which clearly shows this, along with the usual block-treaded dirt track tire.

I suspect however, that the concept of slick, smooth treaded tires for both oval track and road-course work had to wait for two developments: The "wide oval" type of tire, as introduced at Indianapolis in 1964, by Firestone, quickly picked up by Goodyear in 1965, and some of the more complex, almost exotic tire compounds soon thereafter.

With the introduction of the so-called "Wide Oval" tire design in racing in '64, tread patterns went from being a series of rather wide grooves, with all manner of patterns, to an increasingly fine, almost closed, collection of slits in the tread, and the "siping" or slits along the edges of the tread gradually diminished and finally disappeared about 1969-70. 1971 seems to have been the "watershed" year, certainly with race tires in the US, when Firestone and Goodyear both offering tires in USAC, having a curious set of crosswise slots, which angled slightly forward on one side of the tread, to the rear on the other. For 1972, in USAC at least, completely slick tires ruled for the first time.

Tubeless tires appeared in the US, for street-driven cars about 1949 or so, but their acceptance was rather gradual--as late as 1965, one could still by tires requiring innertubes, probably because of the number of cars still being driven with riveted, as opposed to welded, steel wheels. Of course, in racing, tubeless tires had to wait for two developments: Tubeless tires don't work at all well on wire wheels, for the obvious reason that those rims aren't airtight. Even alloy rims lacked air-tightness as well (cast magnesium and even early cast aluminum alloys are rather porous). In the case of magnesium alloy wheels, it took the development, by Halibrand Engineering, of a workable epoxy coating on the inside of the rim to seal the alloy casting against the leakage of any air--this took effect in USAC about 1962-63, other series followed closely behind.

The "inner casing"-"outer casing", or an inner tire inside an outer tire with air between them, as well as inside the inner tire, is not a new thing either! These were developed for street use in the early 1960's by Goodyear, and quite soon they were being used in Nascar, and continued for a number of years afterward, with a corresponding increase in unsprung weight, which probably precluded their use in USAC's open wheel divisions as well as in road-course racing.

Hope this helps a bit.

Art

[Wolf]

Art,a nice expose. But slicks would be a natural thing to develop for oval racing (I take it, oval races were even back then stopped for rain), whereas in road racing one would have to cope with them in changing and rainy conditions- so tyre people would be looking for a 'evolutionary' design of normal, road tyres... BTW, I'm still no big fan of concept of slicks- but I'm venturing a guess that they might provide a better grip with same amount of contact patch (and tyres are narrower for same contact patch area, and hence offer less wind resistance).

[A E Anderson]

Originally posted by Wolf
Art,a nice expose. But slicks would be a natural thing to develop for oval racing (I take it, oval races were even back then stopped for rain), whereas in road racing one would have to cope with them in changing and rainy conditions- so tyre people would be looking for a 'evolutionary' design of normal, road tyres... BTW, I'm still no big fan of concept of slicks- but I'm venturing a guess that they might provide a better grip with same amount of contact patch (and tyres are narrower for same contact patch area, and hence offer less wind resistance).

Wolf,

Of course, a lot of people, from overseas, as well as road-course enthusiasts in the US, continuallly ask: Why, in oval track racing, is a race stopped due to rain?

First, oval track racing is as much about high speed as anything else--it's one of the things oval track fans come to see, and come to think of it, there's little that can compare to the sight of the field at Indianapolis racing the turns at 200+ mph (where else can that be seen, on a relatively flat track--Indy is banked, but at 9-degrees, 11 minutes--nothing at all like a Nascar superspeedway.

At such speeds, even with the added downforce of wings and tunnels, cars are on the very dicey edge of adhesion, and are geared accordingly, and the factor of running out to the limit of tire adhesion has been the hallmark of paved (or the old wooden board track surfaces) since the paving of Indianapolis in 1909-1910 (I suspect the old Brooklands track had similar issues). Even with the use of "rain tires", at a large, high-speed oval, the dangers to car, driver and spectator would be seriously increased. Oval track cars just don't run well at the much lower speeds through the turns as would be necessary for safety, not and perform well at dry-track racing speeds. I still recall watching from the stands, when the almost "Biblical" thunderstorm drenched Indianapolis in 1975--the rain came on so strong (so heavy that it reduced visibility to near zero before the field could be gathered on the front stretch to halt the race as it was run in those days.
Racecars slowed to almost street speeds, and yet there were spins and crashes at 30mph as tires aquaplaned (easy to do with slicks on a car weighing around 1500lbs).

Even on a high-banked superspeedway, such as Daytona, Talladega, or Michigan International, where Nascar "Cup Cars" run no serious wings, the effects would be pretty much the same--their rear end gearing is for top end, and 2nd & 3rd gears in a 4-speed transmission just aren't made for extended running in those gears without eventual failure.

It's just a matter of the type of racing, and the cars being specialised for it.

Art

[A E Anderson]

As a further note to what I wrote about the development of the "slick" or smooth treaded racing tire:

With the development of wooden "board tracks" in the US right after WW-I, racing tires built for use on those high-speed ovals, as well as for use on the brick surface at Indianapolis became smooth, with no tread pattern whatsoever, which continued until both the demise of the board track in the early 30's, and the paving, with asphalt, of the turns at Indianapolis which began in the early-mid 1930's as well.

Bear in mind, that until WW-II, all tires in the US were made from vulcanized natural latex rubber, and in order to withstand the rigors of both street and racing use, the tread compounds needed to be quite hard--much harder than is workable with synthetics..

Art

[Formula Once]

I apologize if this question has been asked and answered before, but when (which GP) were slicks first used in F1 (and by whom). As far as I know it was at some stage in 1971, but I don't know if it was Goodyear or Firestone, etc. Also, was F1 the first category to use slick tires or is it true, as rumour has it, that they were first used in karting? Thanks for any info anyone may have.

[Allan Lupton]

Drag racing was the first to use slicks so far as I remember, and I would have thought that their use in circuit racing would have started at Indianapolis where they didn't race in the rain.
I have a photo of Amon on slicks in July 1971.

[Doug Nye]

Try <http://forums.autosp...ighlight=SLICKS>

DCN

[Formula Once]

Thanks, I knew it must have been discussed here before but I did not find this thread through the search machine.

[Ray Bell]

Originally posted by Allan Lupton
Drag racing was the first to use slicks so far as I remember.....

...with truck tyres that had been retreaded without grooves in the tread. Late fifties?

[Lotus23]

I don't have access to archives right now, Ray, but istr them by '57 or so, by which time I was a regular attendee.

I recall those recaps had a 90 degree angle (with no chamfer of any sort) between tread and sidewall: seemed best in theory, but apparently didn't work as well in practice.

[ianselva]

[QUOTE]Originally posted by Don Capps
[B]I think we discussed this in some form earlier. It is out there somewhere.....

Actually, the Firestone Indy tires were quasi-slicks for a number of yesrs, only three grooves on the outer edges starting at some point in the 50s. The first true slicks were those in drag racing, with M&H and then Goodyear leading the way.

As for GP (F1), I think that there was an Dunlop design from 1968 or 1969 that was close to being a "slick" -- it was devoid any thread, but had a zillion little "x's" all over it. It the the CR-something.


The Dunlops were CR70s and we used them in Minis in 69 I think . I didn't think that pattern ever made it to F1 though.

[AMICALEMANS]

Just to let you know thats Slick appears at Le Mans in 1966, on Alpine Renault and CD Peugeot

[rl1856]

US GP 1960, Riverside CA, Scarab.

Once Scarab decided to leave Europe for good, they spent a good bit of time testing tires at Riverside, with Goodyear footing the bill. At one such test, Goodyear brought along a set of slicks to try. After mounting and adjusting the slicks, supposedly Chuck Daigh was able to shave a few seconds off of his best time.

The tires were used by Scarab in the race.

No one paid attention because the speed of the car was still way off the pace.

Source- Car & Drive Magazine- report published in 1961 or 1962.

Why it took 10 or 11 years for the slicks to be adopted by everyone is still a mystery.

Best,

Ross

[Racer.Demon]

I'm bumping this thread for a related question: does anyone know when slick tyre diameters became regulated in F1?

[arttidesco]

I'm bumping this thread for a related question: does anyone know when slick tyre diameters became regulated in F1?

IIRC the rear tyre diameters were 'frozen' at 26" from May 1976 (Spanish GP) onwards, but I no longer have any of the contemporary literature to confirm this.

[Doug Nye]

Copyright Photo via: The GP Library

Lest we forget - Dunlop's pre-war Brooklands Outer Circuit track tyres were 'slick' in all but name.

DCN

Edited by Doug Nye, 24 August 2012 - 21:06.

[Lee Nicolle]

I suspect the early nearly slicks were siped as to let the tread 'squirm' a little for grip. It also lets the tyres release excess heat. They do that a lot on Sprintcar tyres still. Ultimatly slower but it makes the tyre live, and also they contradictorily build up heat quicker too.
It will sometimes make an old tyre usable again too.
A slick with 2 or 3 radial grooves works better cold than a slick as a steer. Great for hillclimbing unless you buy special hillclimb tyres that go 'off' within mile.
The wrinkle wall tyres are still used. The Sports Sedan Dunlop 16" rear tyre, a 325x700x16 is wrinkle wall and it is radial. They put power down very well on slow corners. Great for powerfull reasonably light cars.
Speedway tyres nearly all are too. But are bias belt.Different manufacturers have very different tyre construction methods to acheive similar ends.
The semi slick radial, nominally a road tyre are the same. Bridgestone have a very rigid [and heavy] construction whereas the Toyos are very flexible and quite light. And are very similar in speed though some spring and shock changes really are needed.
And the Bridgestones are a real chore to fit too!