Fate Has a Long Arm

June 2013

I was driving back from the gym when I suddenly heard a whap-whap-whap coming from the left front of the car. It sounded as though I'd picked up something on the tire and it was slapping against the wheel well. I turned into a side street, stopped and took a look, moved it forward a little and looked again, but everything seemed normal. So I set out again, and the thumping resumed, but soon stopped. I turned around, drove back and scrutinized the roadway where I'd been but didn't spot anything that might have been thrown off.

When I got home, I carefully felt around the tire and found that the inner part of both front tires were eroded away, down to the steel belt, as I discovered when a wire stuck me in the finger! However, with such low ground clearance, it was impossible to see any sign of such extreme wear until I turned the steering wheel all the way to the side.

• Corvettes come equipped with "Goodyear Eagle F1 EMT Ultra High Performance Summer" tires. EMT stands for "Extended Mobility Technology," referring to the capability to drive for up to 50 miles at 50 mph after a loss of air pressure. This is necessary because the tires are so large there wouldn't be room for a spare in the trunk, which is otherwise quite capacious – there is room for two, wheeled carry-on suitcases – our usual luggage complement – with a surprising amount of space to spare. And even a space-saving spare wouldn't be suitable, because not only are the rear tires wider than the front, but they're also taller.


• The "Summer" part means "it is not intended to be driven in near-freezing temperatures, through snow or ice!" Perhaps they assume you have another set of winter tires for the rest of the year. Or more likely, it's from the lawyers, saying don't blame us if you wreck when it gets cold!

Seeing missing rubber along one edge, I realized that the whapping sound must have been caused by a strip that had peeled away from the tread, but was still attached at one end – until it broke loose. My first thought was that it was my fault; that it had been too long since I'd had it aligned. Then I remembered that I had it aligned the last time I was there; although ten months earlier, it was only 3,500 miles ago!

So now I thought they had actually misaligned it. I called Criswell Chevrolet and made an appointment to get two new tires, but I was concerned about whether it was safe to drive there – about twenty miles away in Gaithersburg, mainly over high-speed roads.

Then I remembered OnStar, to which I had continued to subscribe after the initial trial period expired. One high-profile benefit is automatic crash notification, so they can contact you and/or send help if necessary, since they know where you are. Another feature is locating the car and, if necessary, disabling the engine, in case of theft.

So far, the only services that I had used were remote door unlocking, when I had accidentally locked the coat containing the key fob in the trunk, and hands-free calling using their higher-power-than-hand-held-units cell-phone link. Unfortunately, that useful feature has since been discontined.

However, they also listed road service, and when I called found that indeed they would arrange to have my car taken to the dealer aboard a flatbed truck. When we arrived there, the operator told me it otherwise would have cost about $150.

Since I believed it was their negligence that had caused this dangerous condition, I asked them to notify me when they got to my car. When they took me back to the shop, it was even worse than I thought. This is the left tire, showing the section where I figured the whapping rubber strip had been.

It looked like the edge had been ground down even past the steel belt, although it hadn't resulted in any detectable symptoms, e.g., steering pull or tire imbalance. You can see that there are still thousands of miles of tread left on the rest of the tire. However, I carefully scrutinized the alignment test and saw that it actually was within specs.

So it wasn't an alignment problem, and it took me quite a while to determine the cause. I eventually concluded that it was a combination of three factors: aging tires, the type of alignment used on performance cars, and even the way run-flat tires are constructed.

• Rubber compounds harden and lose elasticity with age, due to the effects of heat and oxygen – no doubt you've observed the effect on old rubber bands. Although the damage was along the inner edge, the mechanic pointed out other areas that had small cracks in the tread. I've since learned that although there is general agreement that ten years is too old, several automobile manufacturers recommend replacing tires after six years, regardless of tread life.
  
  Although tires include a four-letter code indicating the week and year they were made, I hadn't thought to check mine while I was there. However, I later found that the remaining, left rear, original tire (the right rear tire had been replaced earlier) was manufactured only a short time before the car itself – the code was 2808, or the week of July 7-13, 2008, which was just now approaching five years. (The 2009 model year began in August 2008, which is when the car I ordered was built.)


• The alignment part has to do with camber, which is the amount the tire tilts as seen from the front. There will be the least wear if the tire is perpendicular to the road (zero camber), while performance cars tend to have the bottom of the tire tilted out slightly compared to the top (negative camber). This provides a better footprint on the pavement while cornering, but it also increases pressure on the inside edge of the tires during straight-line, that is, most, driving.


• Finally, the very design of run-flat tires compounds the previous effects. To be able to support the weight of the car after a blowout, the sidewalls are much more rigid than on a normal tire. In addition to resulting in a harder ride, they provide much less resilience for that part of the tread in contact with the pavement.

Incidentally, tire pressure monitoring systems, now required on all new cars, were first developed for use with run-flat tires, since underinflation wouldn't be noticeable.

I imagine most Corvette owners rarely encounter my problem. Corvette forums reveal that many wear their tires out well before the 22,000 miles mine lasted – "spirited driving" is often mentioned, and one forum is even called "smokinvette.com" – and, in any case, sooner than five years.

Fortunately, once more the good-luck fairy was looking over our shoulders. If the tread strip hadn't separated in just the way it did, I probably wouldn't have had a hint of any problem until a blowout, at best, or total sidewall separation at worst.

And, if the serendipitous discovery of the blood clot in Betty Lou's leg hadn't kept us near home, the previous week we'd have embarked on a 400-mile trip to my high school reunion in upstate New York. Even if we weren't out of cell phone range in some remote part of Pennsylvania when a tire failed, it's unlikely that we'd easily locate the necessary specialized replacement(s).

For example, Criswell Chevrolet had four of the necessary tires in stock, but they also had 76 new 2013 Corvettes on hand, while the Internet revealed that Sutliff Chevrolet in Harrisburg, probably the largest city we'd likely to be near, had all of 5 new Corvettes available.