Reducing lenght r/3 infoobjects.

hi xperts,

I am facing problems with the Transfer rules :

BW SIDE - LENGTH R/3 SIDE- LENGTH

0CPSTCLC- 17 0CPSTLC-BWGVP-19

0VALUE_LC - 17 0VALUE_LC-DMBTR-19

0QUANT_B -- 15 MENGE----

17

How can i reduce the length of the R/3 side objects,as the objects are SAP objects.I am using the DATASOURCE 2lis_03_bf.

Please give some solution.