Not really a C3 question although I may be shopping for tires for my '78.

Had my '78 on jack stands working on my brakes(other threads), put the wheels back on and put my parents '90 Buick(<20K miles) on stands to flush the brake fluid. Its had slow leaks in two tires for a long time so it was a good time to get that fixed figuring a bead or valve stem leak.

Took them to a local tire dealer and was told they won't even put air in them as they are too old! IIRC, the guy said past the date by two years. Searched a bit but hadn't ran across anything firm on that. Some say they won't touch anything over six years.

So, if you have something old with low miles and OEM tires, you can't even get a flat fixed. I did read where some have ran into that situation also.

 

I am curious if the experience was from a chain it independent shop? I would expect an excuse from a chain.

 

This was at Discount Tire, a chain.

 

In general, tires are considerred too old after a period of around 6 years from manufacture.
Rubber actually deteriorates with time, getting harder and can form cracks which become weak points and can cause blowouts unexpectedly.
It is a safety issue.

I guess the tire shop you went to is doing the right thing in advising you.... and of course, hopefully making a sale.


Here's a link with some explanation....
http://www.bridgestone.com.au/tyres/.../care/age.aspx

 

They probably feel that an old tire is dangerous, due to dry rot, belts moving/going thru the rubber, etc. Especially w/ your parents, but f/ the safety of everyone, tires should be replaced every couple or three years. And it sucks not having many miles on a set of high dollar tires and having to trash them. I have been in that situation afew times, as I've never driven far to work or done alot of just cruising. My 'Vette tires are getting some age on them, and I'll be trashing a set of tires real soon that have little tread wear. I guess that we could go out and do a bunch of brake starts to slick them out prior to trashing them. LOL! Atleast we may not feel as guilty.

 

The chemical process that is used to adhere the rubber tread to the steel belts in radial tires breaks down over time. It doesn't matter if they are stored for 6 years in a dark room, in a vacuum, after 6 years there in no guarantee that, that chemical process has not broken down.

This happened to me. When I bought my 72, I knew it was an older restoration, but I didn't know how old. the tires looked brand new, and had full tread - it wasn't until the tread on my rear drivers side tire decided to come of while I was driving 75 down the highway that I found out the tires were old.

Do you remember the Firestone incidents? That was after it was decided to use a bunch of tires that had been stored in a warehouse for four years.

If tires are older than 6 years, then the adhesion between thetire and tread may be gone. If that has occurred, there are two factors that further contribute to the tread seperating. The first is heat, and the second is speed. So if you need to drive acar with old tires, take it easy.

 

It belonged to my parents, they are long gone now. I could easily say that there lots of six years old tires on the road today. My '09 Ford Escape was built in 10/08 and <8K on it!

 

Not a crack on these, cornering wear on the fronts and the rears are like new.

 

Whatever the apparent condition of your tires, the time span given by that shop is valid. I ran into the same situation this spring and found warnings from chains and small independent tire shops to be very consistent. By 6-7 years of age, they'll tell you it's time to replace them. Between my research and then talking to a bunch of car buddies, I decided it was time to replace all 4 tires on my 69 before I went drag racing in May. The old tires looked good for the most part and had a lot of tread left but it was just time for the sake of safety. By the way, a local independent shop knew they couldn't get the tires for me that I wanted but they still strongly recommended getting new ones even though they had nothing to gain.

 

Here's what can happen when the chemical process holding the tread onto the tire breaks down. When the process has broken down, the rubber being hot and soft, and traveling at higher speed, with centrifugal forces pulling the tread away from the center of the wheel, is a recipe for disaster.

These are pictures from my tire, and believe me, it did a heck of a lot of damage when it came off.

 

Tires are much more complicated than most people think. Almost all the tires available for the C3 15 inch rim in the corvette sizes are quite frankly junk. The 255/60/15 as an example is almost exclusively available as a speed rated S (112mph-minimum DOT rating for a passenger tire)/T(118MPH) tire. The speed rating is really not just for your reference about the max top speed of the tire but tells the end user much about the tires construction strength and it ability to resist temperature buildup. I have a few cars and not one of them runs anything less than a Z rated tire not because I run the cars above the Z rating (open rating above 149 mph with a sub rating of W (168 mph) or Y (186 mph) but because I want a tire that is very STRONG in its construction and uses the best quality rubber (aka traction in the dry and wet). My 2001 pontiac grand prix has 225/55/16 ZR ultra high performance summer only tires, as an example, because of the strength of the tire and traction capabilities-the car couldn't go above 110 MPH. I switched to 17 inch rims on the 78 a few years ago because I could not get an ultra high performance tire in the 15 inch rim so I switched a to a 17 inch SLP rim and run 255/45/17 ZR summer only tires.

With all that said, I would abide by the 6-7 year time frame for a S rated 15 inch tire. I have 245/45/17 ZR's on my 1994 Mustang GT Convertible that are 10 years old on a car under a car cover in the garage except when out, with zero dry rot and no tread cracks-I am not in the least worried about those tires. Looking at the tread separated in the pictures above, I would guess a BFG Radial T/A S rated and would not run that tire more than 7-8 years regardless of condition due to the weak tire construction. Everything I say is predicated on running the proper tire inflation-under inflation will blow certain tires quickly due to the heat buildup. Hope that helps!

 

Your not worried about your ten year old tires but would a tire shop touch them? They should because they are Z rated?

The car in question here is also garaged but not covered.

 

i was commenting on my estimation about the useful life of tires? Obviously, a shop could care less what the rating is on the side wall if they are making comments about age.

I have never had a tire shop check the manufacturer date on a tire sidewall when I have needed service-Just my experience. I would surmise that tire shops refusing to balance, mount, etc older tires have an ulterior motive-MONEY. As long as they note on the receipt their comments about working on older tires was not recommended, ultimately the owner of the tires would be responsible. Just common sense.

 

Yes, they want to sell a set of tires just not repair them. It's easy to say that they can't touch them by law. I plan on double checking what other dealer's policy is when it comes to this.

 

Safety is a big deal to me also. However, sometimes I drive my car a few miles over the government posted speed limit. Sometimes I go 3500 miles between oil changes and sometimes I even drink milk a couple days after the expiration date.

I have no doubt that a tire loses some integrity over time. I am also just enough of a capitalist to think that if I got $20 I can find a guy who will patch that tire. It's just a matter of finding a guy who wants the money more than he fears being sued.

This is America, if motorcyclist can ride without a helmet, I should be able to get a 7 year old tire patched if I have the cash.

Every time I have taken my daily driver to a chain for an oil change or some other service, they say I need an air filter and hope I will say yes. The filter is fine. It’s just a way for them to boost sales and meet their corporate quota. Some regional sales mangler sent an email that says to refuse to work on an out of date tire and instead pitch them a new set.

 

The condition of a tire depends on a lot of variables. Time is a big one, but if the car is driven with some regularity, garaged where tires are not in sunlight that much, kept clean, and pressure is maintained, a good quality tire should last at least 6-7 years. Of course, it is up to the owner to check them over regularly for sidewall cracking, or sidewalls are not smooth (rippled or lumpy). Any indications of tire integrity problems after 6-7 years would be cause to replace them.

 

I have thrown tires away w/ good tread that were much less than 6 or 7 years old. I feel that it depends upon the quality of the tire and the type of driving you're doing. I'm NOT going to run a tire on a long trip, or at high speeds if the tire is three years old or more. Maybe I'm cutting the time line alittle low, but if my life or my family's life is depending on those tires, I'm just not taking the chance. I had a high dollar performance Good Year tire slip a belt as I was coming into North Carolina off of I40 from Tennessee going through the mountains. I felt a vibration that wasn't there a minute ago as I was coming down one of the mountain hills at about 85 mph. I had the family in the car w/ luggage in the trunk and on a 5 week vacation. The exit I took just happened to have a tire shop there that carried Good Year Eagle tires in the size I needed and we were on the road in 40 minutes. I don't wear tires out, as I don't drive very far f/ any reason. (I posted that above). In my opinion, I don't think that someone should run tires on a vehicle f/ more than two or three years, maybe if you only go to the corner store and back in that vehicle. It is true that the tires we have available f/ the 15" rim on our C3s are not of the best quality. I've posted this afew different times in the past. I read not long ago that the down side of the brakes on the C3 is the quality of tire that is available f/ the 15" rim. I think that JB78L-82 did the right thing in going w/ 17" rims, as that is the only way to ensure safety at high speeds and hard cornering.

 

After seeing mashman's pictures, I wonder if anyone REALLY knows why the tire makers started using steel belts? I remember that they were using aramid and kevlar for the belts, with no problems. Kevlar is suppose to be stronger than steel and is what is in bullet-proof vests. Remember the state troopers killed using the new steel belted radials at high speeds? I feel that the steel industry lobbied for the steel belts to be put in tires, because they were losing all of the beer and soda can manufacturing to the aluminum can manufacturers.

 

Steel is cheaper. That's about it.

Texas Jim... I'm not really 'pickin' at ya; but if your family's safety is so important, why were you going "down the mountain at 85 mph"?

 

Not taking it as picking; here in Texas, we drive 85 often. I make sure that my vehicle is in good order and I'll drive 85. I run a steady 80 and 85 on long trips. In a vehicle that's up to snuff and myself driving, I have no problem w/ it.