A 9” wide tire in the front is fine. Anything wider and you may encounter interference issues within the steering knuckle. As for you going with 26” tires all around. Are your current set of tires different sizes front to back..? Like 25x10-12 Rear, and 24x8-12 Front..? If so, I would keep the offset sizes as changing to 26” all around may cause your 4wd system to bind. But if your current set of tires is 25” all around, then your good to go to 26” on all four corners.