I was just curious as to if someone put a set of 12 inch rims all the way around on an 06 Honda Rancher ES 350 4x4 would it mess anything up. I got a set of 27 inch tires that came off of a RZR and i need to get a set of 12 inch wheels to make it work. With mine being a solid rear axle I do not believe it would mess anything up. I just thought i would ask around to make sure. I already put a lift kit on it to make it work, just need to make sure the wheels will work before i spend $300 on a set of itp wheels.

 

Yes it would mess it up. Your bike is 4WD so the front wheels have to cover the ground at the same rate as the back ones, bigger outside diameter tyres cover more ground per revolution so the front end would be trying to go at a different speed to the back end which strains the transmission. Note this refers to the OD of the tyre so you can't just fit bigger OD tyres on one end and not the other either.

 

I think the guy is staying with 27" tires front and back his question was he needs 12" rims for the tires to work since the 350 has 11" rear rims.

The ATV all ready has 12" rims in the front so really all you need is two new rims for the back, just make sure the off set and bolt pattern are the same as stock and your good.
The fronts have less extra space so make sure nothing will rub if the 27" tires are wider.
You will loose a lot of performance since a 27" tire is a lot heavier then the stock 24" tires it came with especially on a 4wd 329cc.

There is a guy on this forum (Beer Gut) who put 28" tires on his smaller Four Trax 300 (282cc). I think he has some pics of it.