CEMB USA C75 (A) User Manual

Page 23

I 0202 - 23

SOLUTION:
Rotate the tyre on the rim by 180°

Example 3

Rim 0 mm

Tyre + 1.2 mm

Wheel + 1,2 mm

Eccentricity of the wheel cannot

be compensated by the rotation

because the rim is perfect!

wheel

rim

tyre

rotation axle

Ideal wheel

RESULT:
no improvement is obtained

5.7.1 - PRESETTING OF TOLERANCE ON THE MACHINE
There is no general rule concerning acceptability of an eccentricity value . As a fi rst approximation we
consider it correct to use a threshold of 1 to 1.5 mm. The E/ECE/324 standard prescribes 1.5 mm as
max. eccentricity of a rebuilt tyre.

5.7.2 - VALUE OF STATIC UNBALANCE, CORRELATED WITH ECCENTRICITY
Clear indication is given in the Measurement screen of both the value and position of the static unbalance
as well as the eccentricity. In fact, it is interesting to check the correlations of the two values, above all of
the two positions. When the two positions have a similar angle (± 30° one from the other), there is a clear
sign that an eccentricity is present which can be compensated by matching.

5.7.3 - VALUE OF UNBALANCE CORRESPONDING TO ECCENTRICITY
For user’s reference, the centrifugal force is calculated corresponding to a certain speed, compared to
the force generated by the eccentricity present on the tyre (calculated with an approximate average
elastic constant).