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RE: Free tire-purchasing advice

To: mgs@autox.team.net
Subject: RE: Free tire-purchasing advice
From: thorpe@kegs.saic.com (Denise Thorpe)
Date: Wed, 19 Jun 96 15:11:09 PDT
Finally, the original post showed up so I can respond to this.  Look what 
you started, Jay. ;-)

Wes Grady said:

> I really hate to throw my $.02 worth in here, knowing the temperament of =
> you (yes, you Denise!) autophiles, but

Moi?  I know, I've been told before that I have too many opinions and too 
many facts to back them up. ;-)

> While I am an attorney and not a tire man any longer, I did sell and =
> manage a tire shop for 4 years, and represent both two large tire =
> companies and a regional tire association.  Much of the misinformation =
> that is floating about in regards to tires was (is) the result of =
> someone's conceptions and not grounded in fact.

Gee, I've managed to avoid conceiving so far...

> Wire wheels can most certainly be balanced on a computerized tire =
> balancing machine.  It is done all the time and done correctly.  While I =
> am sure that there are a lot of tire shops that don't do it right, there =
> are a lot of tire shops that don't balance anything correctly.

In a later post, you supplied a procedure:

> Anyway, sure, wire wheels can be balanced on a computerized balance =
> machine.  Procedure is real simple.  Every unit has an adapter that puts =
> a cone on both the front and rear of the wheel.  This allows the wheel =
> to spin free and as long as the wheel is true, you balance it like any =
> other wheel/tire combination.  Now, here is the real secret.  If the =
> wheel is out of true, rather than screwing around with it, balance it =
> anyway and put it on the rear of the car where it will probably not be =
> noticeable.  If it is really bad, it has to be trued by hand and most =
> tire shops don't have the time to do this. =20

Here are some more facts:
There's a difference between the true of the wheel and how true it's 
mounted on a tire balancing machine.  A trued wheel can still be mounted 
incorrectly on a tire balancing machine.  From my experience using 
computerized tire balancing machines, the two cone trick doesn't work 
because of the reason I already gave--the outside cone is pressing against 
a surface that was never meant to align with the rest of the wheel.  The 
best that can be achieved this way is to split the difference between the 
true of the machined surface and the error in the outer surface of the hub.  
The way to find out if the wheel is really balanced is to loosen the outer 
cone, rotate the wheel a little, and retighten the cone and see if the 
machine still says it's balanced.  I could never get this to happen and 
believe me I tried when I had free access to a tire balancing machine.

The two cone method will give an acceptable (for most people) approximation 
of balance, but it's not right.  If it wasn't acceptable, fewer people 
would drive LBC's because there aren't enough little old men with wire wheel 
hubs mounted to their benches to go around.  However, when Britcar people 
ride in my car, they're impressed by how smoothly it rides.  Ask Andy Ramm.

Okay, here's the trick to balance your own wheels:  
Do it on the car.  You have two wire wheel hubs mounted on bearings on the 
front of your car.  Back off the brake pads however you choose, and mount 
a wire wheel (if not already mounted) securely.  Take off all the weights 
first.  Oh yeah, and put the car in the air before that.  Tap the wheel 
with a hammer that won't mar it.  This should encourage it to rotate so that 
the heaviest part is lowest.  Put successively larger weights on the 
opposite side of the wheel (the top) until the wheel can no longer be 
encouraged to rotate.  Then mark the wheel and hub so that you can always 
put it back on in the same orientation because you've just balanced it along 
with the brake rotor.

To balance the wheels that will go on the rear, you should balance it on the 
front after picking the side with the least variation in the rotor.  You can 
determine this by changing the orientation of the front wheel you just 
balanced and seeing how much of a difference it makes and comparing this to 
the results of this procedure on the other side.  Balance the rear wheel on 
the front and then mount it on the back.  This still won't be truly balanced 
but it'll be close.  

I have the little old man do this because he's mounting the tire anyway, and 
he's better at it, and he has a big assortment of weights, and then it doesn't 
matter which wheels go on which hub, and I like him.

Denise Thorpe
thorpe@kegs.saic.com

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