Mich do own BFG.
They no longer make the KM only the KM2 so I guess they are waiting for stock in that size. Other more popular sizes are allready in the UK (265/75, 255/85, 235/85 etc)
you should fit extended arches for wider tyres (12.5") and I personally dont think its wise going over 35" without further modificatons especially with a more aggressive tread pattern.
+ your gearing will be screwed >35s
JMO
G