Better tires up front?

[EquatorHeat00]

Should the better (more tread depth) tires be up front on a car because thats where the steering is. If you have a rear blow out you can still steer right?

[EquatorHeat00]

Nobody knows?

[wolfdogs]

Nobody knows?

actually, yes, i do know.

yes. always place the best tires up front, injury wise and tread depth wise. f not so much for blow out purposes, but for handling purposes. the deeper the tread ...the better the change of direction response. its always better to have the car oversteer slightly than to understeer... which is what you would get with the deeper tread on the back...in most conditions.

if you have a front blow out...you can control the car..you just have to know what to do.

i had a write up on my old website on controlling a blow out. its gone now... but im in the process of doing another one for our operations here at work... so ill post it here when im done.

[wolfdogs]

here you go, this is a draft of my new blow out paper:


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.

Ken Collings
GSA Fleet Operations

[Z Ya Later]

Very nice writeup Ken. I'll definitely keep that tucked away in my mind.

[95TransAm]

Nice writeup also.

Something to definitely pass to friends and family. Information like that can be a life saver...i don't hope that i have to test that anytime soon...but non the less very important information.

Thanks for taking your time to post it.

[wolfdogs]

your'e welcome guys. i posted the original one back in 98...and have gotten 3 emails from f body folks that said it saved them from a possible crashi. i hope nobody has to use it..
just remember it