Gently used 2004 Chevrolet Corvette - needs new tires?

Maintenance/Repairs
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Dear Car Talk,
I own a Corvette that I bought new in 2004. It has about 15,000 miles on it now. I keep it garaged for the winter and only drive it in nice weather - you could say it is ‘gently used’. My question is about the tires. I had read somewhere that even though you may not have a lot of miles on your tires, if they are old, they could still be corroding on the inside. I asked a good friend of mine who is in the car business, and he said if they were corroding, you would see ‘cracks’ on the outside of the tires. We looked at my 2 front tires (2 rear tires were replaced last year because I picked up nails in each one) - and they both look good on the outside. Still, I wonder if there is anything going on inside that we can’t see.
Is it worth me getting 2 new front tires to be on the safe side, or can I trust that if there is no outward signs of decomposition, the inside is ok?

Thank-you,
Jane

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Original tires ? If so they are 14 years old and should be replaced . I know Corvette tires are expensive because I have had to buy them also. 10 years is the maximum time for tires even low miles and miles. Your good friend does not know what he is talking about. Why take a chance on failure at the worst possible time?

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Thanks for your input. I agree better to be safe than sorry!

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Even IF there is not cracking on the outside of the tire, the tread is harder than the pavement by now. Rubber just gets harder with age and the tire’s grip just goes down as the hardness increases. It would be treacherous in the rain and just plain bad even in the dry. Replace those other 2 tires, pronto!

You ARE the atypical Corvette 1st owner! Many years and little mileage.

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The fact that this is a performance car calls for the two older tries to be replaced. However we have a phobia on the site about tires becoming “instruments of death” after 10 years. It’s a lot like how long is a piece of string?

Years ago, a mining company in North Africa found several WW II military trucks half buries in the Sahara sand. They had been there for 40 years. The uncovered them and the tires were still pristine and had the original air pressure in them.

I do a lot of industrial part warehousing design. My clients keep rubber components in a dark, climate controlled room within the warehouse.

To get maximum safe life out of your tires, store the car indoors and out of sunlight. Heat and ozone destroy rubber eventually. Miles of use and roads driven on affect tire life as well. A car always parked inside and driven infrequently can easily go 15-20 years before it really needs new tires.

I have three family members with farms and they don’t use anything like 10 years to replace the many rubber tires on their machinery.

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@CapriRacer Would you like to comment on this thread as you are an actual tire authority ?

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My experience with old tires is that they do get hard and slippery over time, but that is sort of a crust on the tread surface that wears off over about 100 miles. In the first 100 miles watch out for damp pavement or hard braking, because you will skid easily. The tires I’m writing about are tires that have been unused for years, but stored in the dark. The OP tires are used on and off, so the “crust” may not be too big a deal.

The other thing to check is the valve stems. You should give them a good wiggle and pull on them, too. They can also deteriorate over time, and you’d hate to have one of those pop off while you’re driving.

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I’d replace them, the rubber gets hard, as said above. Why have a Corvette that doesn’t handle like it should?

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Good point.

I put a set of new Michelin Pilot 3 tires on my Miata recently after I decided the old ones were starting to get a little thin and showed their age (12 years). The difference was really quite surprising, quieter ride and much more secure handling.

That said, I understand both sides. Paying nearly $1,000 for 4 new tires is a big bite, and one we do have to think through, but I suppose in the long term whether I buy them this year or two years from now makes no difference in the long term cost of the car.

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At least for the OP it’s only 2 tires.

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Farm equipment isn’t operated at high speeds that generate the heat car tires experience. It is also not catastrophic if your tractor tire goes flat, vs. a blowout at highway speeds. This Corvette sounds like it is driven more like a Camry but I wouldn’t want to mess around with bad tires on a car like this.

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Don’t compromise your safety. Replace all four tires at the same time. Can’t go wrong with michelin tires, though they a bit pricey. If you are looking for something more affordable, check out the BFG G-Force Comp-2 or Hankook Ventus V12.

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Common sense says to replace them. but if you only use your Vette for the occasional 35 mph run to 7-11 for a big gulp, you might can get away with just keeping an eye on them for any signs of cracking. If you have a problem, it will show up in the drive wheels first most likely, which is the rear I expect in a Vette. A flat rear tire at 35 mph shouldn’t produce that much of a handling problem. A burst front tire is more problematic , even at 35 mph.

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George , get serious . Using a Vette for a big gulp run at 35 MPH ? And yes it is rear wheel drive and it has new tires on the rear . Apparently these tires are 14 years old and with the little ground clearance a Vette has a blown tire could cause expensive damage to the Vette.

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On occasion I get low mileage sports cars in with original tires, 2001-2005. They are garage kept so no dry rot but they do get hard with age, some owners complain about flat spotting that takes 5 to 10 miles of driving to work out. Sometimes I make right turns at 15 MPH and these old tires can be rather slick but most of these people drive like they have a bowl of hot soup in their lap, they don’t know what grip is.

A “blow out” is very unlikely, after years of obvious dry rot sometimes the belts separate, that draws attention to the driver.

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I bet you could sell the low mile c5 and use the money to buy a c6. With new tires

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Sure.

Disclaimer: I am not a rubber chemist, but I’ve worked along side some talented ones and have picked up quite a few things. So take what I am about to post with a grain of salt.

Rubber deteriorates over time. I think it is mostly attack by oxygen. Tire manufacturers put antioxidants (AO’s) in the rubber to sacrifice themselves instead of the rubber itself. You can sometimes see these as a rust colored film - although other colors are possible.

There are also waxes embedded in the rubber matrix that form a barrier to slow down the deterioration. You can sometimes see these as a whitish film. Both the AO’s and the waxes flake off as the tire flexes, but the flexing allows the waxes and AO’s to migrate to the surface, replenishing the barrier. Yes, they will eventually be used up.

In a modern steel belted radial tire, it is the rubber around the belt edges that is of most importance. That is the most highly stressed area of the tire. Unfortunately, you can’t see what’s going on in there, so we use cracks on the outside as an indicator.

Unfortunately, some tire manufacturers use certain types of rubbers that are not prone to cracking in their sidewall and that disguises the condition of the internal rubber.

Further, cracking is a combination of the condition of the rubber, and the amount of flexing it has undergone. So tires not frequently used aren’t as likely to be cracked - as is the case here.

Put another way, if a tire is cracked, it should be removed.

  • BUT -

Lack of cracks doesn’t mean a tire is good. That’s where the age thing comes in.

I am of the opinion that heat is the major driver of rubber deterioration (Arrhenius’s Rule), so tires in Phoenix don’t last as long as tires in Minneapolis. I think the appropriate age of removal is 6 years and 10 years respectively. Places in between are …… ah …… in between.

If some rubbers aren’t as prone to cracking, why not use those? Because they don’t work well in certain areas of the tire, and the belt edges is one of those.

What about tires dressings? I am of the opinion that they generally cause more harm then good, because many of them remove the wax barrier. The exceptions are those that have antioxidants.

Oh, and avoid using tire dressings that have silicone in them. Every tire slippage problem I investigated involved silicone somewhere. Armorall is one of those (or at least, it used to be!)

Now about those WW2 tires. Those are bias tires and those work differently than modern radial tires. Not only don’t tires from that era perform at the level modern tires do, they would be expensive because of the excessive amount of rubber used in them (which is not to say that heavier modern radial tires are better. It’s a lot more complex than that!)

So to address the OP: Replace those 14 year old tires. You don’t want that car damaged when the tire fails as the usual failure mode involves a large flap of the tread (and top belt) coming partially off and beating the fender to pieces. (see videos of race cars)

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Thanks everyone for your responses. I think I’m going to err on the side of caution and replace the 2 front tires !!

Jane

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You’ll feel better after you get the new tires, because you are worrying about them, and you’ll feel a lot better after you pay the credit card bill.