Have you ever heard of the Pirelli 4 PSI rule?

The procedure is to inflate the tires to a known pressure.

Go on a long drive. As soon as you pull over, measure tire pressure
again.

If the tire pressure has risen more than 4 PSI, that tire needs more
tire pressure when cold. If the tire pressure has risen less than 4 PSI,
that tire needs less tire pressure when cold. Adjust gradually when cold
so that you get to learn the required starting pressure.

This technique goes back over half a century and can still be found
on the web in their warranty information.

 

Pirelli 4psi Rule....interesting....never heard of it....but going to do some searching on this....interesting.....

 

FINAL:
With new shocks, poly upper shock mounts, poly wishbone bushings and old worn tires, took in for alignment.
Caster and Toe were both out of spec.


Tech tells me that toe was not out enough to cause that tire wire and neither would the caster settings.
He would only set the toe under the alignment fee; setting the caster would be extra and he did not schedule the time for it. I was a bit put-off with this, but I do understand the time/effort required to change-out the shims.


Anyways the Caster numbers are:
LEFT: 5.7° range of 5.9 to 7.3
RIGHT: 5.5° range of 6.6 to 8.0


So left not too bad, but right is out alot. So I came home and rechecked my notes and sure enough...I put the right side shims on the same as the left side....WRONG!


So since I had the wheels/tires off getting the new tires put on, I once again took the right side fulcrum bolt out and switched around the shims. I am hoping that this improves the caster number, but not going for another alignment at this time.


I could not find any information as to what location of the shims does exactly what. If anyone could point me to that info I would appreciate it. All I have is that a thin shim changes 0.2°, thick shim 0.4°.


So until I know that I am not going to change anything else. Just going to keep a close eye on tire wear.


Thanks again for all the help, could not have done this task without the forum help.


Later

 

Don't sweat the caster. swapping the shims should be good enough. In the US, its not like we are driving down crowned country lanes. I drive mostly in the passing lane of 4/6 lane roads and the crown is opposite what the caster is supposedly set for.

 

Forgot to mention brakes: I did clean and re-grease the sliders; no more steering wheel shaking upon moderate braking. Suspect problem was OEM bushings.