Need new rear. bt56r unavailable? bt021 ok to mix?

[06Busaking]

I have a 06 with oem rear tire. Front only has 3000 miles on it.

They are both oem bridgestone BT56R tires.

I can't find the BT56R anymore, and if I can it's at FULL MSRP plus shipping.

The BT56R is a bridgestone Battlax. I've found two other Battlax's, but have different numbers. The bt015 looks almost identical to my BT56R.

Thoughts on mixing these two tires? Or any ideas on where to get a BT56R at less than MSRP.

Bridgestone Battlax BT 015-E 190/55ZR17 RR Tires - BMW K1300S - Competition Accessories (This is a pic of the BT015)

http://www.tyre-pictures.com/Bridgestone/BT56R.jpg (pic of the bt56r)

 

[sixpack577]

BTO15 isn't the greatest tire by far, but the BTO16 is alot better(sport tire). The BTO23 is the sport touring tire. BTO16 front and 23 rear is a good combo. The sport touring rear will last alot longer and still stick well in curves. Keeping a sport tire on the front also gives you great traction where it counts.
I'm running the Dunlop equivalent of those (Q2 sport front/Roadsmart sport touring rear), and the rear is wearing at the same rate as the front. With a sport tire on the front and the rear, the general rule of thumb is that one front tire will last as long as 2 rears.
The softer the tire compound the better they stick, but they obviously wear out the fastest.
If those tires are original or have been sitting for a long time I'de replace the front too.