So I am watching Motorweek on the Speed Channel and during the Goss' Garage section they are talking tires. They covered the when to change old tires etc.....

I did not know you could tell the week and year a tire was produced by looking at the dot stamp on the sidewall of the tire. So I go and check my tires and find they are 13 years old (second week of 1993). I think it might be time to change them for safety reasons. I don't want to be going 100MPH and have one blow out due to the age, although the tires have alot of tread left and don't seem to be cracking. Are they just helping to sell more tires or would you change?



A typical Pre -1999 DOT number GJHV234319

GJ= Manufacturing plant code
HV234= other production information
319= date code 31st week of 1999 (9=1999)

A typical 2000 up DOT number BTFR872001

BT= Manufacturing plant code
FR87 other production information
2001 = 20th week of 2001 (01= 2001)

interesting ...

gotta go and check mine ...
Andy

Yup.....the old pharts on the 356 list were discussing the same thing. Some of those guys are driving on tires from the 80s.....I bet rocks have better grip....

I just checked mine, various sets:

Yokohama = 115 = 11th week of '95
Kumho V700s = 1700 = 17th week 2000
other Kumho V700s = 259. midway through 1999

Makes a lot of sense.

Thanks for the info

R

I think good yokys at 13 years means Yokohamas rule!!!


Cool.

OK, what does it mean if there is no DOT stamp. My 185/70 15 on 914/6 are Uniroyal Steel max and do not have a dot sticker. Tred look like it came off a rally car. When I autocrossed it for the first time last month it really slid all over the place. Fun and controlable but not real fast. About 4 seconds slower then my 4 on more modern rubber, and on a fast course really designed for 911's.

it means your tires are from the '70s, probably as old as the car and should not be used for anything other than to roll it around the driveway ...

Andy

The son of a good friend of mine is a tire developement engineer for Goodyear in Akron. He told us some time ago that the rubber in tires typically loses a large percentage of their performance capacity within five years. They are best when new and go downhill from there.

I read this same thing in a Road & Track article this past year. Various manufacturer's tire engineers indicated that five years is considered old for a tire.

I currently have an old set of Yoko Intermediates on my car and the rubber feels hard as a brick. I know it's time for replacement, not from lack of tread, but from old age.

After a pretty good accident involving some stupidity on my part, I don't even consider old tires useful for filling with air. Nowadays, I always use a positive-locking air chuck hooked up to one of those tire gauge/valve combo dealies, with a 10-foot hose and a really good 0-100 PSI dial gauge just to be absolutely positive about the pressure that it the tire. Old tires are like hand grenades only less predictable, as far as I'm concerned.