Pumba

Gentlemen,

I am noticing more and more the debate about tire age. Most of what I read is formulated by emotion, not by technical or scientific data.

Personally, I had to forego participating in a new race series because my tires did not meet the sanctioning body's three-year age limit. I purchased my Michelin PS2 tires new in May of 2011. The new 285/30R19 front tires have a date code of 2610, meaning that they were manufactured at the end of June, 2010. They were 11 months old when they were mounted on my Z. The new 325/25R20 rear tires have a date code of 5208, meaning that they were manufactured at the end of December, 2008. They were 29 months old when they were mounted on my Z.

In my professional background I spent some time as an OEM tire-wheel engineer. With that background I contacted the Rubber Manufacturers Association in Washington, DC. RMA is the trade association that represents all of the tire manufacturers that you can think of.

The following is RMA's official policy on tire age:




If facts are what you consider, the debate is over about tire age.
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lefrog

The main fact that I get from their statement is that 'temperature, storage conditions, and conditions of use' are determinant in the tire use.
I agree that age alone is not a sufficient factor to determine tire condition (but the same applies to race seats, racing harnesses, window nets, helmets, etc...).
Racing organizations expiration dates might seem arbitrary sometimes but they have to draw a line somewhere. They usually don't have the equipment or knowledge to assess if a particular component is sound according to their original safety specs so pretty conservative expiration dates are used to minimize the risk. It's part of the game. You can probably find another club that has rules that have more common sense but most of them have dates on everything.

That said, even if you try to keep tires in good storage condition, rubber deteriorates over time. I got a set of brand new R-Comps for free because they were 9 years old and even though they were properly stored, it was impressive to see how the tire came apart in just a day of AutoXing.

Pumba

Would you list for me the names of the sanctioning bodies that have tire age limits?
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troyguitar

There are no lap times or skidpad numbers in the statement you posted. How is the debate over?

We're talking about racing, not driving to the grocery store.

In what universe are your old PS2's going to have a chance in hell against new Rivals?

Pumba

The point of my post was to make Forum members aware of the facts about tire age.

It is not about lap times or skid pad times. It's about being allowed to compete. For business reasons BFG does not make Rivals in sizes that I can use. If they did I would consider them.

troyguitar

Who are you expecting to compete with?

A PS2 made yesterday isn't going to compete with a new PSS, let alone any of the 200 treadwear tires that are allowed in these events... an old one is likely to be even worse.

You have ZERO chance of winning on old PS2's whether you actually take the green flag or not. Zero. Zilch. Nada.

Scooter70

Thanks for the actual tech Jim.

I assume that you mean 2010.

RX-Ben

The age limit may be based on trying to boost tire sales to a series sponsor or driven by insurance concerns. Do you really need 20s in back?

Pumba

Matt,

Yes, thanks for the note. I have changed the text to 2010.

Pumba

I need a minimum of 19s to clear my brakes and to keep the rim from rubbing on the upper control arm during full rebound.

In addition, the Michelin 325/25R20 has a 13.0 inch tread width. I would have to go to a 345/30R19 tire to get as wide a tread width (13.2 inch), and the sidewall of that tire is not as stiff in the lateral direction as my 325/25R20 tire.