question tundra 26 inch PA18-150

Hi guys, we have a pa18-150 with 800x4 wheels and 1.1 / 4 axles. We want to put tundra 26 wheels on it. Can you tell me what we need? if we can do it with the original tires and axles or should we change them.
Over there I heard that they use longer shafts, can it be?
I hope for your help, thanks

Welcome!

You'll need 6" wheels for 26" goodyears.

Tell us about your brake setup.

You can use your gear but will need 6" wheels and brakes.
https://www.airframesalaska.com/Alaskan-Bushwheel-199-71-Wheel-and-Brake-Assembly-p/abi-199-71.htm or
https://www.airframesalaska.com/Cleveland-199-71-Wheel-and-Brake-Kit-p/199-71.htm

Then after you fly it a while you will want brake boosters and then Bushwheels and on and on and on. 8)

I have a gently used set of GY's in the hangar if you decide to go that route.