Tyre age and Safety

Maybe someone here can offer sage advice?

A year or so ago I bought some Avons (3 x rear 4.00x18 and 2 front 100/90x19) when I realised they were likely to be in short supply soon.
I put each in a black garbage bag, sealed and labelled them and put them in the relative cool downstairs.
I have now fitted one rear, but am wondering when the others may be considered unsafe to use?

They are all made in 2022, between weeks 13 and 38.
Age alone cannot be the determining factor, otherwise what is the point of keeping them in a dark, sealed & cool environment.
Doing so would obviously be to keep the volatiles that keep them from going hard from escaping.

So - is there a way (durometer maybe?) to determine their suitability for fitment in the future?
Cheers

I do not know how to test them as asked. But IMO they are safe for many years when stored like that.

They be fine to use my mate use to store tyre for many years when was sponsor bye a tyre place when racing kept in the dark under his beds in the house m tyres for his Harley and dirt bike, anyway Rob put them on and we will keep watching, and if anything does happen, nice knowing you, no only joking, if there are no sign of cracks on the sidewalls they be good to go.

Thanks for the advice guys!
I have also just ordered a Shore A Durometer to play with and get a feel for what readings I get from a variety of good tyres.
I'll also find some older tyres, obviously past their use-by date for comparison.
I'll report back on my findings.
Cheers

robs ss said:

Thanks for the advice guys!
I have also just ordered a Shore A Durometer to play with and get a feel for what readings I get from a variety of good tyres.
I'll also find some older tyres, obviously past their use-by date for comparison.
I'll report back on my findings.
Cheers

Click to expand...

Many years ago on the Brit-Iron mailing list, this question was asked and generated (as these things do) a lot of traffic. Charles Falco, who at the time was a professor of Physics at the University of Arizona, had a durometer and tested a lot of tyres of various ages. As far as I remember, his conclusion was that there was a rapid change over the first 6 months to a year, then not much. He did find a lot of variation in his results though and basically concluded that there was no clear evidence either way.

SteveBorland said:

Many years ago on the Brit-Iron mailing list, this question was asked and generated (as these things do) a lot of traffic. Charles Falco, who at the time was a professor of Physics at the University of Arizona, had a durometer and tested a lot of tyres of various ages. As far as I remember, his conclusion was that there was a rapid change over the first 6 months to a year, then not much. He did find a lot of variation in his results though and basically concluded that there was no clear evidence either way.

Click to expand...

Typical academic… generating more questions than answers !!

I have heard that tires age from the inside to the outside.... So there's that for ya.

You never know what tyres are going to do until you use them. A durometer only tests the surface of the rubber. When tyres heat-up, they usually give more grip. Some guys seem to fret if they have a moment. You obviously do not get on a bike and fly up to the first corner, and chuck it in. Everything has to do with feel, and working up to speed slowly. With race bikes, everything changes as you ride them, and you compensate for the changes. With a road bike, you are often going into corners cold. It is more dangerous. Tyre warmers on race bikes amuse me. Some guys blame cold tyres for their crashes, when it might be a cold rider which is the problem.

Fast Eddie said “Typical academic… generating more questions than answers !!”

Actually Charles Falco is a real motorcyclist who rides a lot, including a cannon ball run across the USA on a pre 1930 motorcycle that he restored. He is extremely knowledgeable on a lot of subjects. If there was a definitive answer he would have given it. Goes by Magnetoman on British Bike forum. I remember his tyre article.

I might shock a few people. Back in 1974 or 1975 we experienced major shortages of most things including oil and oil products. There were all kinds of calls by a vocal minority to ban all vehicles over 2 litres and even less in some cases. Motorcycle tyres were almost impossible to get. I found Jim Eade in Sydney had a few K81s in so I raced over and bought four. Two went on my bike straight away and the other 2 were boxed up and stored. After that I started running Metzlers then Avon so I never got to run the K81s. Just over 10 years ago I restored a side valve Ariel which cost more than I had allowed so when I found the old box of K81s I thought I will fit them for the run in period of the bike, during which I would be unlikely to exceed 80kph. The majority of the run in would only be at 60kph as side valves are notorious for nipping up due to uneven cylinder expansion. As the 40 year old tyres looked good I fitted them, completed the 1000 mile run in and then as the tyres still felt good I did another thousand or so miles before putting the bike into storage. The tyres are only just now showing a few cracks in the side walls, and will be replaced if I decide to ride the bike again. But they are now 50 years old.

Remember the Worlds Fastest Indian when Burt Munro used boot polish on his tyres to hide the cracks.

ando

I bought a race bike once that had been built to a fairly high standard 10 years prior, and not used at all.

OBVIOUSLY I wouldn’t race it on 10 year old Metzeler race tyres… I’m not stupid… no one does that.

But for its first run out I didn’t have time to swap the tyres, which didn’t really matter as I only intended to shake it down.

After a few steady laps, the red mist dropped, and I flogged it for the rest of the weekend.

The tyres felt fine to me. So they stayed on all season.

The bike threw a rod on the last lap of the last race of the season and totalled the engine. So, actually, those tyres out lasted the engine !!

I did however fit new tyres… and engine… for the following season.

My bsa rocket 3 came to me with a 2002 tax disc so hadn't been used since at least then
The front tyre was a ribbed Avon deathmaster that was like a piece of carbon
I changed it out for a road rider
The rear k81 was absolutely fine and it's still on there
I've no Idea how old it is but it grips the road fine

Fast Eddie said:

Typical academic… generating more questions than answers !!

Click to expand...

Actually, he's a fascinating character. Rides a lot, knows more about much stuff than most people ever will, and really good at communicating it.
Amongst many other things, he is a dedicated collector of motorcycling books - his aim at one point was to own a copy of every book published
Along with a couple of other people including Brian Slark, he was very involved in the Guggenheim exhibition "Art of the Motorcycle". As far as I know, it still holds the attendance record for an exhibition.

From https://en.wikipedia.org/wiki/The_Art_of_the_Motorcycle :

The Art of the Motorcycle was an exhibition that presented 114 motorcycles chosen for their historic importance or design excellence in a display designed by Frank Gehry in the curved rotunda of the Frank Lloyd Wright-designed Solomon R. Guggenheim Museum in New York City, running for three months in late 1998. The exhibition attracted the largest crowds ever at that museum, and received mixed but positive reviews in the art world, with the exception of some art and social critics who rejected outright the existence of such a show at an institution like the Guggenheim, condemning it for excessive populism, and for being compromised by the financial influence of its sponsors.
The unusual move to place motorcycles in the Guggenheim came from director Thomas Krens, himself a motorcycling enthusiast, supported by a novel corporate tie-in with BMW. The motorcycles were chosen by experts including Krens, physicist and motorcycling historian Charles Falco, Guggenheim advisers Ultan Guilfoyle and Manon Slone, and others. The exhibition was described by historian Jeremy Packer as representing the end of a cycle of demonization and social rejection of motorcyclists, followed by acceptance and reintegration that had begun with the mythologized Hollister riot of 1947 and ended with the high-end marketing of motorcycles and the newly fashionable biker image of the 1980s and 1990s. Or at least the show served as "a long-overdue celebration of the sport, the machines and the pioneers they love."

I missed it much to my regret, but the catalogue is wonderful.

And now, back to the scheduled program...

robs ss said:

Maybe someone here can offer sage advice?

A year or so ago I bought some Avons (3 x rear 4.00x18 and 2 front 100/90x19) when I realised they were likely to be in short supply soon.
I put each in a black garbage bag, sealed and labelled them and put them in the relative cool downstairs.
I have now fitted one rear, but am wondering when the others may be considered unsafe to use?

They are all made in 2022, between weeks 13 and 38.
Age alone cannot be the determining factor, otherwise what is the point of keeping them in a dark, sealed & cool environment.
Doing so would obviously be to keep the volatiles that keep them from going hard from escaping.

So - is there a way (durometer maybe?) to determine their suitability for fitment in the future?
Cheers

Click to expand...

Dunlop used to say they are good for max 6 years, installed or not. AFAIK, Avon doesn't give a range.

Dunlop motorcycle tires now says: "Tires are composed of various types of material and rubber compounds, having performance properties essential to the proper functioning of the tire itself. These component properties change over time. For each tire, this change depends upon many factors such as weather, storage conditions, and conditions of use (load, speed, inflation pressure, maintenance etc.) to which the tire is subjected throughout its life. This service-related evolution varies widely so that accurately predicting the serviceable life of any specific tire in advance is not possible. Tires which have been in use for 5 years or more should continue to be inspected by a specialist at least annually. It is recommended that any tires 10 years or older from the date of manufacture, including spare tires, be replaced with new tires as a precaution even if such tires appear serviceable and even if they have not reached the legal wear out limit."

It seems to me that there have been enough advances in tire technology in the last 10-20 years that comparing what was made 7 years ago with what is made today kind of makes it hard to directly compare.
And the _old knowledge_ a bit obsolete.
Even on our ancient bikes.

marshg246 said:

Dunlop used to say they are good for max 6 years, installed or not. AFAIK, Avon doesn't give a range.

Dunlop motorcycle tires now says: "Tires are composed of various types of material and rubber compounds, having performance properties essential to the proper functioning of the tire itself. These component properties change over time. For each tire, this change depends upon many factors such as weather, storage conditions, and conditions of use (load, speed, inflation pressure, maintenance etc.) to which the tire is subjected throughout its life. This service-related evolution varies widely so that accurately predicting the serviceable life of any specific tire in advance is not possible. Tires which have been in use for 5 years or more should continue to be inspected by a specialist at least annually. It is recommended that any tires 10 years or older from the date of manufacture, including spare tires, be replaced with new tires as a precaution even if such tires appear serviceable and even if they have not reached the legal wear out limit."

Click to expand...

...a tyre manufacturer recommending a tyre to be replaced even if it appears serviceable. Wow! Go figure!

Thanks Greg! Hope you're travelling okay!

When I road-race a motorcycle, my brain is glued to the rear tyre contact patch. If it is moving too much, I ride slower until I get grip. I never just fly up to a corner on the first lap and chuck it in. It always takes me about 5 laps of a race circuit to get up to speed. If it rains, I am always in with a better chance. Most people these days believe tyre bullshit - always adapt to conditions. If you need more grip lowering tyre pressures can help.

acotrel said:

When I road-race a motorcycle, my brain is glued to the rear tyre contact patch. If it is moving too much, I ride slower until I get grip. I never just fly up to a corner on the first lap and chuck it in. It always takes me about 5 laps of a race circuit to get up to speed. If it rains, I am always in with a better chance. Most people these days believe tyre bullshit - always adapt to conditions. If you need more grip lowering tyre pressures can help.

Click to expand...

You find relevance a challenge don't you?

robs ss said:

You find relevance a challenge don't you?

Click to expand...

Keeping things relevant and answering questions about his utter bullshit are indeed a challenge