Ok, this may be a dumb question, but I'm not well versed it tire ediquet. My 04 sportsman has 25x8x12's on the front and 25x11x12 on the back.

am I able to go with 26x9x12's on the front and 26x12x12 on the backs? Is it unstable to go with a little wider tire on these rims? will they tend to roll more? or is is totally fine to make that switch? any help would be appreciated!

 

You have enough room to go with a taller tire front and rear and you have enough width in the rear to go with a wider tire. But depending on which tire you choose to use in front you may end up with a clearance issue between the wider tire’s inner sidewall and the outer tie rod ends if you stay with the stock wheels.

Aftermarket wheels have a 1” wider offset so you’d gain 2” in width (measured on your tire's center line track). This puts some room between the inner sidewall and the outer tie rod end. Even if you can mount up your 9 wide front tires on the stock wheels and you have a little space between the tire and the tie rod end boot, if your tire picks up any mud it will trash the boot and the tie rod end in short order. Best to go with aftermarket wheels, steel if you don’t want to spend the $ or aluminum to save weight. If you have questions or want a quote these guys can help you out.