danglerb

Here is a blip from tirelitigation.com which may apply to way too many of use who put very few miles a year on our cars.

DOT Number: The federal government requires that all tires sold in the U.S. contain a Department of Transportation (DOT) number. The DOT number contains very important information about your tire that most people do not know is there. However, the DOT number is often found on the axle side of your tires, meaning you have to crawl under your vehicle or put the vehicle on a lift to read it. Perhaps the most important information contained in the DOT number is the date of manufacture of your tire. Many U.S. and foreign tire companies are now warning consumers in Europe and Asia to discard even new appearing tires that are five or six years from the date of manufacture. This is because the rubber and other components in tires break down over time, making older tires potentially dangerous even if they look brand new. Although manufacturers do not give similar warnings in the United States, this is likely to change as lawmakers and watchdog groups including trial lawyers put additional pressure on tire companies to follow the same safety guidelines that are applied overseas.

To determine the age of your tire, find the last three or four numbers on the DOT code – these represent the week and year the tire was built. As an example, the last three numbers "089" might signify that the tire was born on the eighth week of 1999. Unfortunately, not all manufacturers supply the decade, so this tire might be a 1999 or a 1989 model. Fortunately, the government has seen fit to resolve this confusion in the new millennium, so tires being built now have four digits: two for the week and two for the year. Be sure you know the age of your tires, and don't risk your safety for the few dollars (relative to an accident) that a new set of tires will cost. This is especially true for your spare tire. Your spare may have been exposed to the sun, or may have been placed near the heat of your exhaust pipe. If so, it is likely that the rubber compounds in your spare have been substantially weakened even if the tire looks brand new, which could cause a catastrophic failure if you later place the spare into service. If your spare is more than 5 years old, consider replacing it when you buy a new set of tires, even if the spare has never been used.

Dave H.

i'd like to have an alignment that would let me get 5 years out of a set of tires...

69gaugeman

Me thinks you might have bwaah pedal alignment issues

928ntslow

I think if you have tires that are 5 years old, you ain't driving the car enough. Average 15K to 20K miles for tires before you have to replace them. Thats 4000 miles a year on the high side. You'll have more issues to deal with other than tires if that's all your doing.

danglerb

Classic and collector car status often includes a 3k/year mileage cap doesn't it?

I doubt I will put 3k on mine, errands and family stuff will be in the big car.

I was in the Porsche shop the other day and several of the cars had nice looking until you get real close old tires that have no business at anything like the rated speed.

Plus the 5 years is from date of manufacture. If a tire inventory isn't being rotated properly, lifo instead of fifo, then a "new" tire could be a year or more old before it ever goes on the car.

fabric

Isn't tire life affected simply by exposure to elements, not just age? exposure to sun and ozone I think decrease tire life the most. If the tire are kept out of the zone in a climate controlled environ, shouldn't they not dry out so much?

This seems a bit like engine oil, that there shouldn't be a hard and fast rule, but that for the unwashed masses, it's just easier. I suppose with tires, as Keith says, most folks simply wear them out before they get this old.

Sharkbody

Fill em w/nitrogen and coat them with 303 protectant inside and out (exterior). G

H2

I wouldn't trust those tires at 155mph.

H2 (i.e., HH)

AO

My 20k mi tires seem to only last about 4k miles.

Joe '87 S4

I'll be replacing my tires some time next year because of age and not mileage. They're 5 years old and have a little over 21,000 miles but they could easily make another 5,000. Rubber doesn't last forever. But, climate, type of use, etc., all have a different effect on the wear and tear the tires take. It's the same for the timing belt. I'll be changing that because of age and not mileage also.

the flyin' scotsman

I've had my car for 5 yrs and its on its 3rd new set of tyres ~ 40k kms means they're only lasing approx 15k kms a set and thats without a SC..............yikes.

Bill Ball

5 years! I do a tire and oil change at the same time each year.

danglerb

Tires have a certain amount of "goop" that goes inside when they are made, and over time it dissipates and the tire begins a much more rapid deterioration. Modern tires are extremely robust, but normal use puts very very little stress on them. Romp around town, leave a few black stripes, even a few freeway blips zoom and slow back down, and I wouldn't worry much. More than about 5 minutes at speed and I think you are rolling the dice with older tires.

Its not like 5 years and poof, more like 2 or 3 years and a gradual degradation begins, and the tire begins to harden and lose compliance. How its used, how its stored, must make a difference, but I don't know what or how much. When just one tire was replaced on a warranty issue, I paid to replace the second one and put the "good" old tire in my storage a few years ago. Maybe I will dig it out and look it over.

I don't want to give anybody on the list a coronary, but I put Pep Boys finest on my Mustang and they are now pushing something between 30k and 40k miles, but that car for some reason has always had perfect alignment.

danglerb

BTW I brought this up mostly because many of us bought cars that have been parked or driven very little by the PO, and all we may see is the good tread and shiny armorall on a tire that might actually be totally beyond its safe lifetime for driving at speed.

If its not already in the PPI, there should be a line for check manufacturing date on tire sidewall.

Imo000

Danglerd's research is correct. I've known about the manufacture date code for a while now. Amazingly fery few people do and even less that tires have shelf lives.

I was under the impression that 6 years is about the max you want to use a set of tires. Offcourse most of use never have this problem on a 928, but it can be if you have a set of winter tires for a DD. They very well can last 6 years, but by that time they are pretty much work out anyways.