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Tire Age
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Author:  Frank T [ Mon May 27, 2013 9:14 am ]
Post subject:  Tire Age
A few years ago, Ross gave us a great Post which described how we can read the code on our tires, to determine exactly when they were made. The point was, even when you buy new tires, they may have sat on the shelf or been in-transit to the retailers and actually be years old before you unwrap them.

I can't find that post now.

Ross, if you don't mind, wouldja/counldja please re-post that info for us?
Thank you, Sir.

R/S,
Frank
Author:  jtang [ Tue May 28, 2013 11:41 am ]
Post subject: 
It is a 4 number "DOT" code.

First 2 numbers indicate week and last 2 numbers indicate year.

for example, DOT 3211 means the tire was manufactured on the 32nd week of 2011. :)

Some tires only stamp this on one side of the tire, so check both sides.

Here's an example I pulled from google:

Image

Age is one measure but it is important to know how the tire was stored too. If indoors a tire can last a very long time. The set of tires I ran last season for autocross were 2003 production, but they were stored indoors and kept dry. I have also seen tires as new as 2008 with dry rot and cracks. I think the typical number age limit is 6 years, but give or take depending on storage and tire design.
Author:  Datsun Z Garage [ Wed May 29, 2013 9:22 am ]
Post subject:  re:
I've also heard you should not store tires near electrical motors or generators, as they put out ozone which will age the rubber.

You never know....when a tire store keeps tires in the "back room", they could be sitting next to a transformer, etc.
Author:  Frank T [ Wed May 29, 2013 9:47 am ]
Post subject: 
I wonder if there's any really 'safe' way to buy tires anymore? When I was a kid, I remember seeing them lined up in racks outside the gas stations, baking in the sun and enduring the weather. I guess times have improved since then, but anytime you're putting your life on tires traveling 90+ mph, you want a little more assurance that they aren't going to come apart under you.

This would be a great subject to get Burton Brown involved in. He's trying to push his Z car over 200mph this year at Bonneville, and of course tires are a primary concern for him.
Author:  jtang [ Wed May 29, 2013 1:21 pm ]
Post subject: 
Most reputable tire places will have the sense to store them properly. Tire Rack is an excellent source for tires. They not only have many brands of passenger tires, but they also have competition tires, R-compounds, and many "exclusive" competition tire models. Racers have trusted them for years, and for good reason!

Also as a rule of thumb, the softer the compound, the easier a tire can get hurt by age. As a comparison, "old" for passenger tires is 6-8 years, but "old" for R-compounds is 1-2 years.
Author:  Datsun Z Garage [ Wed May 29, 2013 1:52 pm ]
Post subject:  re:
The generator warning always made me think of an old gas station with 'sale' tires in the back room.

FACTOID: Costco used to let you bring in your own tires and they would mount/balance them for you for a fee.

But they changed their policy several years ago...I remember I emailed them to complain. They replied with a convoluted reason that 'paying' customers shouldn't have to wait for non-Costco tires to be mounted. That I was a member and I was also paying to have them mounted didn't seem to occur to them. Luckily there was Tirerack.
Author:  jtang [ Wed May 29, 2013 2:25 pm ]
Post subject: 
Yes... it's a cheap excuse to discourage people from buying tires from outside vendors. Many tire shops are doing this as a practice now. :?
Author:  Frank T [ Thu May 30, 2013 7:54 am ]
Post subject: 
Here's an interesting nice-to-know list of all the DOT manufacturer codes, updated to 2010.

Somebody went to a LOT of trouble to compile this list:

http://www.harriger.com/tires.htm

As you can see, the example in the photograph above was made by CX, which is Toyo tires of Miyagi Prefecture, Japan.

I did notice that M9 was the Uniroyal tire company of Middlebury CT (spelled wrong).

Frank
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