Landracing Forum
Tech Information => Technical Discussion => Topic started by: Bigtime on November 15, 2014, 10:12:11 AM
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Besides tire grinding when skidding, puncturing or so.
Is tread separation the ultimate limit for a high speed tire?
What can be done to prevent it?
Do land speed tires have some reinforcing cords embedded in the tread to prevent centrifugal force from pulling the tread apart?
Something like
http://www.google.co.in/patents/US3991803
If so, How do they make sure such embedded cords won't actually concentrate stresses in the rubber thus creating a breaking point?
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Besides tire grinding when skidding, puncturing or so.
Is tread separation the ultimate limit for a high speed tire?
What can be done to prevent it?
Do land speed tires have some reinforcing cords embedded in the tread to prevent centrifugal force from pulling the tread apart?
Something like
http://www.google.co.in/patents/US3991803
If so, How do they make sure such embedded cords won't actually concentrate stresses in the rubber thus creating a breaking point?
There are a lot of failure modes in high speed tires, centrifugal force can pull the bead away from the rim resulting in air loss, tread chunking, and wear due to tire spinning are others. Tom Burkland did some tire testing, a lot of tires just disappeared when spun fast enough.
Go ask Goodyear, MT and M&H how they make their tires....
You could read
http://www.landracing.com/forum/index.php?topic=8282.0
or search tires with the search function to see all that has been discussed over the last 10 years or so...
let us know what you find out :-D
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This is one of those issues that I still believe tire age has a big influence. Rubber has a shelf life (from very pliable to hard and brittle) and yet lots of land speed guys run old tires. I've had guys bugging me for my old front Top Fuel tires to use once I'm done with my solid aluminum ones. The tires are 20+ yrs old (no way I'd make any kind of pass with them) and yet guys still do. I'm curious... with all the safety precautions the SCTA tries to take, why do they allow old tires to be used?
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Here's a quick aside about tires and their age: Motorcycle tires must be less than 10 years old to race at Bonneville. UNLESS - they're race tires and that fact is displayed on the tire itself (in other words, you can't get away with saying they're for race-only). Inspectors check the date code on the tires - or find the race-only wording. Either way it is noted on the inspection sheet.
I don't know the car rules, but I do know that I've seen some pretty elderly tires in use. Over to you. :|
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... Is tread separation the ultimate limit for a high speed tire?...
Make what you will of this: Mickey Thompson's first set of tires on Challenger1 had no tread rubber at all. For its first public display, they used black paint to make them "look" more like tires.
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Some folks shave the tires to reduce the amount of rubber on the tread, and consequently, the magnitude of the rotational forces that try to tear the tread off.
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In the early 90's before the new 30" Mickey's came out, we were running 1960's Firestones beyond 400 & even scuffing into the cords on some runs without failure.
A real LSR tire doesn't have a whole lot of rubber on it so there's nothing to take off. A treaded tire on the other hand, it's better to buff them down to lose the mass & also true the tire at the same time. Age is definitly going to be an issue with this type of tire.
Sid.
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Late 60's.....early 70's.....many OLD Indy tire were used.
They ran many with cords showing.
One exceedingly dry year many of those tires spun themselves into oblivion.
Exact facts escape me. The principles are true.
FREUD
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We ran some old 18" Indy's in 89 but they would throw chunks of rubber in the high 300 range & then they'd shake like all $hit. We were guilty of giving some of the old Firestones "a hair cut" when they had only a couple of layers of cords hanging out & running them again. It's kinda like the end of Speedweek when you wear your cleanest dirty shirt. :-D
Sid.
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Yeah I have seen Al attack a tire with a razor blade.
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Well, like most things.... it depends.
For this discussion we should be talking about high speed "race tires" as opposed to street tires.
If we are talking about a tire failure it most likely is the bead that will fail. If we are talking about shredding that is a condition where the tread (what there is of it on a high speed tire) is peeled off the tire carcass and becomes unusable but did not "fail" as it still holds air and save your ass. The shredding of the tire can be caused by a couple of things including age but the most common cause is spinning the tire. This wears through the thin top coat of rubber (.030?) exposing the cords. If the cords are wore through they can continue to "peel" back at high speeds. Most Bonneville type race tires have a very thin "tread" as opposed to a street tire so shaving is not required but some people use tires the were not manufactured for LSR type racing and may indeed shave the tread down so as to not induce tread separation at high speed.
In regards to my comment about bead failure; this is a catastrophic failure and we don't see this type of problem to often.Gene & Tom Burkland have spun many more tires than I but I think they have come to similar conclusions in that if the tire is spinning faster than its designed construction it will most likely fail at the bead. It would be nice if Tom jumped in here.
Almost lost this post again. It's a real pain in the arse when the website program "helps" you keep from reposting pictures. Then you change the name on said pictures only to be told you've already posted this text. What a pain & it's happened more than a few times and I have just said forget it.
I have posted a few pictures of Bonneville tire construction and shredded tires
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Here are a few more pictures showing a tire "chunking" along with a "blistered" & "flat spotted" tire from a spin.
Adding a few words here because the website hates me..... :evil:
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This is one of those issues that I still believe tire age has a big influence. Rubber has a shelf life (from very pliable to hard and brittle) and yet lots of land speed guys run old tires. I've had guys bugging me for my old front Top Fuel tires to use once I'm done with my solid aluminum ones. The tires are 20+ yrs old (no way I'd make any kind of pass with them) and yet guys still do. I'm curious... with all the safety precautions the SCTA tries to take, why do they allow old tires to be used?
Because there's usually nothing wrong with them. Your experience with tires is probably limited to general consumer type stuff where you're putting thousands of road miles on radial street tires that live outside in the sun all their lives. LSR tires live a very different life from regular street tires. Rarely are LSR tires pliable and in fact the better ones are usually very, very hard. Most LSR tires don't even have enough rubber to even be consider "tread". Most LSR tires are on a car and in the sun only for race events. When not at a race and actually racing, most race tires come off and live in the garage. Most LSR tires are run a fairly high pressures so there's little flex and little heat developed except in some extreme cases. Old school tires like the Firestone Bonnevilles have many, many plies in their carcass (something like 16) and you can remove most of the superficial "tread" rubber and run right down to the cord. We haven't run our roadster in a while but it has 'Stone Bonnevilles from the 60's on it and I'd be comfortable taking those tires to 200mph.