Not to mix radial and bias?

[tanker]

Gents,

I am riding the wear bar @ 8000 miles on the rear OEM `Stone. The front tire can hold for another 8K so I am only changing the rear one. My main concern safety and handling - the more I research the more I see it emphasized that bias and radial tires should not be mixed because of the different handling characteristics. A 180/70/16 bias `Stone would still be an upgrade to the OEM and I`d switch for a radial front and rear setup for the next tire change. Whaddayathink? Also, it makes me think - if the radial tire is absolutely superior to the bias ply, why is the Nomad sold with bias skins? The load bearing capacity the only thing I can think of.

Other Q. Is any one of you running AMSOIL? I`ve tried it and after 4K it is still a smooth shift, feel and sound. I wonder when to change it given its added extra (?) sheer protection. If I have to change it in the normal interval, then there is no point is using the more expensive oil - it is hard to believe that it would be so superior to the other SYN oils. Any AMSOIL user out there?
Thanks a lot!