I have 27x9 front - easier to steer, and 27x 12's in the rear and they work really well. The blackwaters have worn really well too, the sales person said they would wear quickly but they haven't. Keep an eye on your wheel alignment, my freind ruined one of his new bear claws because it wore funny, due to misalignment.

 

When you put a 12" wide tire on a 7" or 8 " wide rim the tire bulges and makes the tire taller than the front tire of the same size. Tire height and weith is hard, mfg's can measure the tire inflated or uninflated and then allow 12mm.. That is why some 27" tires fit a quad and another brand of 27" will not.