[Healeys] Wheel or Tire Shake

[Tom Mitchell]

Discount Tire (and I'm guessing others) has a machine (at least that's what
they told me) that runs the tire and wheel at speed.
We had a bad (new) tire that was out of round, you could see it move up and
down. 
As a side note: I had to push them to find a solution, as they kept saying
everything was fine.

Tom Mitchell
1965 Austin Healey BJ8 MK3

-----Original Message-----
From: healeys-bounces at autox.team.net [mailto:healeys-bounces at autox.team.net]
On Behalf Of Joe and Lenore Armour
Sent: Tuesday, July 07, 2009 9:46 AM
To: Healey
Subject: [Healeys] Shake

Please do not assume that when your tyre has been dynamically balanced 
that you have necessarily eliminated all potential causes of vibration. 
Should the tyre be out of round, flat spoted etc. or as has happened to 
me with a new wheel the rim ( not spokes) had not been manufactured 
correctly, the wheel/ tyre can have weights added to compensate for the 
dynamic forces generated by the out of true. BUT when you return the 
assembly  to run on the radius of the tyre/wheel any dimensional error 
and out of tolerence will cause the wheel to rise and fall each time 
that point comes in contact with the road surface. Additionally a 
defective tyre may appear true at the low speeds used to dynamically 
balance them but at speeed and with heat it can deform to an out of 
round state. The join in the tread is often the point at where the 
dimensional accuracy fails. Thus balanced on a free standing axle or 
machine shaft is no guarantee of  NO SHAKES
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