not good!
They both handle SO differently from each other,it can cause loss of control at highway speeds over 35 and up..if you MUST "mix" radials and bias ply tires,put the bias ply's up front..
I tried using some bias ply studded snow tires on my van I had hanging around in excellent shape..figured studs would be nice in the snow..I put the all season radials up front,studs in the back,and went for a long ride to visit my brother up north..I did fine until I got onto a wet highway onramp...at 35 mph,the vans ass end suddenly started passing me!..I did a 180,and came to a stop up against the curb,in the blink of an eye..
I had felt a strange feeling like the front and rear were fighting each other just before the ends swapped..I ended up using the studded tires in FRONT on my long ride instead!..I found it drove ok at high speeds,but did feel "squirmy"..traction wasn't a big problem in the rear in my van,it had lots of stuff in it and was heavy..the studded tires up front actually helped a lot as far as steering..but I took them off as soon as I got home,and put 4 radials back on..
I'd avoid mixing the 2 types..using just one bias ply out of 4 might not be so noticeable,but I can safely say if you put 2 of them on only the rear axle,you'll be doing doughnuts...especially bad on snow or ice,or even wet asphalt..

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