Lost a tire yesterday...

[Joe K. 99 Zeee!!]

Boy, was that a good time.

Was driving back to North Jersey from Maryland on Rt. 95 when some road debris cut my left rear. Not too big a hole, but enough to cause a moderate leak. First thing I felt was that my steering was a little off. It really didn't dawn on me it was a blown tire though. There was very minor wandering for several minutes and then a moderate vibration when the tire finally lost enough pressure. I pulled over slowing gently (as per Ken's e-mail ). At no time did I feel I was not in control of the car. All in all the Firehawk Wide Oval tire held up well considering.

Here's some more lessons learned:

-The GM jack works well.
-The GM "tire iron" does not. With only a handle on one side it tends to torqe the bolts to the side. With very tight bolts to loosen, it cross threaded one of my nuts and it was stuck till AAA could come and help out. The walls of the tire iron around the bolt also bent so that it started to strip the corners off my bolts. Get a real tire iron to carry with you.

Ended up limping home on my spare at 55mph. Needless to say I was not the popular car on Rt. 295 or 287 where everyone else is doing 70+.

[Steel2686]

Glad to here you're okay, Joe. Coincidentally, I cut a tire on 287 last year. I was in my S-10 going through Purchase, NY. Changing a spare on the side of 287 is trecherous. Luckily a State Trooper pulled over and threw his lights on for me. It slowed traffic down considerably.

[Joe K. 99 Zeee!!]

Believe me, I pulled waaay over on the shoulder and had my wife watching oncoming cars.


Oh, one more thing. Check the pressure in your spare tire!!! Should be at 60psi. Mine was initially a little lower than that. Don't wait for a blown tire to find out. Apparently the spare in my '99 is good up to 65 MPH for 3,000 miles. Most aren't quite that durable, took me a little longer getting it home, but I was playing it safe.

[Sean 94z28]

I did not think you were supposed to drive with the spare on the rear, even for relatively short distances. Doesn't the difference in tire diameter heat up the differential? I can't remember if its in one of the manuals or on the jacking instructions. I have come out to find my rear tire flat a couple times and was always bummed I had to get a full size off the front first.

Sean

[Joe K. 99 Zeee!!]

Hmmm...I don't see it in the owners' manual for the '99 or '94 model. That would seem to make sense though. Maybe I'll change it to the front when I get back home tonight. New tire should be coming tomorrow though...

[Christopherrr]

Oh, one more thing. Check the pressure in your spare tire!!! Should be at 60psi.

Yeah, I learned that the hard way...it looked fine sitting in the well ,but when I popped it on after a flat...it went flat.

[Dave-S]

A couple of comments the spare, and mounting the spare on the rear. I speak from experience since I had a similar issue two years ago.

As far as mounting the spare on the rear, if you have a rear axle with a clutch pack (such as the Auburn unit), don't do it because you will eventually burn out the clutches in the rear axle because the two tires rotate at different speeds due to their different diameters. If you have the Torsen rear end, there is no problem because they don't use clutch packs.

When it comes time to replace your tire, consider getting at least two new ones. My car had about 6K miles on it when I had to replace my rear tire due to a puncture. I bought only one tire but there was just enough of a difference in diameter bewtween the two on the rear axle that every time I accelerated "briskly" my car tended to push to one side. This may have been a function of the torsen that's in my car but it was definitely something I didn't like.

[Joe K. 99 Zeee!!]

I just replaced the tires less than 1,000 miles ago. Also, I believe GM installed Zexel Torsen differentials on the 99+ f-bodies. So I should be good. It's only going 5 more miles to the firestone to get installed anyway.

[95TransAm]

Glad to hear that it didn't get uglier on the highway and that you were in total control the whole time.

I remember Ken's post about how to deal with a blow out. I'll never forget it...might save my life one day.

I had a flat on my rear driver's side last fall. I wound up switching my front tire to my back, and put my donut on the front driver's side. I know it's better to have the proper tires in the front due to steering, but I didn't know if the difference in tire diameters would kill my differential. Just drove slow and steady the whole way home.

[wolfdogs]

Controlling a vehicle after a tire “sudden air loss” (blow out).

Back in 1994, while I held the position of the Manager of GSA’s Federal Tire Qualification Testing Program, I was lucky enough to be invited and attend a Michelin sponsored blow out training course held out in the desert at the Nevada Automotive Test Center in Silver Springs, Nevada. The course was a week long, hot and dusty, and worth every single second of it. I learned a lot of things about vehicle handling dynamics, and I learned not to fear a tire blow out by safely controlling a vehicle with a blown tire and bring it to a safe stop.

What you are about to read here can save your life….I hope that you will pass this information on to friends, family, and anyone else you may feel might benefit from it. Memorize it…and tuck it neatly away in the back of your mind, but know its there…..so if you do have a blow out…..it jumps out without you having to “think” about it. There is no time to “think” when a tire blows out….it’s the first few seconds that are the most critical.



Lets look at this “blow out” scene……and what’s really happening……….

Force Vector: There is a “force vector” which is present when your car is traveling down the road/highway….this “force vector” is a sum of the forward motion of the vehicle and the input of the forces driving the rear wheels (or front wheels). This force vector has variables….say your front end is out of alignment, this could cause a slight pull to one side, or, and under inflated tire, and misaligned frame from a previous accident (God forbid)…but…these variables are slight in nature. So…..this “force vector” is what makes your vehicle continue its motion in the forward direction, and is only altered by the steering input fed by the change in direction of the front tires………keeping in mind, if that steering change is TOO drastic, the force vector will overcome the change and cause skidding tires or center of gravity displacement…i.e.: rollover.

The dreaded blow out (sudden air loss)……… when this occurs, you now have a new force vector, this force vector has been created by tremendous traction (rolling resistance) now being supplied by the blow tire…its “dragging” the front or rear of the vehicle to that side, the side of the blown tire. This force vector is at a 90 degree angle to that of the forward force vector that’s dictating the direction of the vehicle. Front tire blow outs are much worse than rear because it is “steering” the direction of the vehicle.

So…What do you do?

I’ll tell you what you don’t do first: Never…..Ever…….hit the brakes!
Why? Remember that force vector I described above? If you hit the brakes, you are now drastically increasing that sideways force vector. Hitting the brakes when a blow out occurs is responsible for almost 95% of all crashes that occur during a blow out, especially roll-overs. Most all blow out crashes happen in the first few seconds of the blow out, especially front tire blow outs.

Let’s look at a rear tire blow out condition first: Ease your foot off the accelerator…ease… don’t just jerk your foot off the pedal…the engine compression and deceleration will add to much to that nasty force vector. The whole idea is that you are maintaining control and continuing in the same direction that you were before the blowout. The tire is not going to come off the rim, unless you just keep driving it down the road for a mile or more. When you can, steer over to the shoulder, if there is one, lightly and steadily applying the brakes until you come to a stop. That’s it.

Ok. The scary one, the worst blow out scenario, a front tire blow out:
When a front tire blows out…the vehicle immediately begins to pull in the direction of the blow tire…..accelerate….. yes, your read correctly… accelerate! Only briefly though… Why? Because that increases that force vector of the direction you are going before the blowout…and allows you to get control of the vehicle and maintain course. It only takes a few seconds… depending on your particular vehicle and road conditions. Now, I’m, not advocating stomping on the accelerator pedal if you are driving a Z06 Corvette with over 400HP!... However, if you are driving a fully loaded vehicle with a 150hp 4 cylinder, you may have to do that. You know your particular vehicles acceleration capabilities better than anyone. You must be the judge. Once you have control, then start doing the same thing you did with the rear wheel blow out till you are stopped.

[95TransAm]

And to add on to what Ken just said...

About a month ago, I was traveling eastbound on 290 about 5 miles outside of the Chicago city limits. Out of no where, a white mid nineties dodge caravan cuts me off. Ironically, not 20 seconds later, his front driver's side tire blows out right in front of me. Chunks of rubber were flying in to my windshield. The guy in front of me, although cutting me off horribly, obviously knew how to drive. I noticed him slighly pull on me for a second, then he just coasted and lane changed to get to the shoulder. Only until he was in the right lane did I first notice his brake lights go on. This guy was in a minivan with a high center of gravity, and still managed to pull over like nothing was wrong. Had he decided to slam on the brakes immediately, things could have gotten ugly for the both of us and possibly many more.

Keep everything Ken posted in mind, and safe driving everyone!