Linux – rmem_max more than rmem_default

I just installed centos 6.3 freshly and noticed the following:

[root@localhost user1]# cat /etc/redhat-release
CentOS release 6.3 (Final)

[root@localhost user1]#

[root@localhost user1]# cat /proc/sys/net/core/rmem_max
131071

[root@localhost user1]# cat /proc/sys/net/core/rmem_default
229376

[root@localhost user1]# cat /proc/sys/net/core/wmem_max
131071

[root@localhost user1]# cat /proc/sys/net/core/wmem_default
229376

As you can see rmem_max is "Lesser " than rmem_default and
wmem_max is "Lesser" than wmem_default.

As per my knowledge wmem_max and rmem_max should be more than default values ?

EDIT:

# cat /etc/redhat-release
CentOS release 6.3 (Final)

# uname -a
Linux localhost.localdomain 2.6.32-279.el6.x86_64 #1 SMP Fri Jun 22 12:19:21 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

<<
link : https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/7-Beta/html/Performance_Tuning_Guide/s-network-dont-adjust-defaults.html

Bear in mind that the value of rmem_default should be no greater than rmem_max (/proc/sys/net/core/rmem_max); if need be, increase the value of rmem_max.