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I do a lot of back county flying and a lot of times the landing area is not in the best possible shape. I would like to install 29" tundra tires on it. Due to the change in wheel and tire size do I need to get FAA permission to make the modification and if so what would be the process?

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    $\begingroup$ It's possible that a 337 exists as a one off approval. Join the Piper forum to get that info. If there is no 337, you probably need an STC which is something you can Google. $\endgroup$ – acpilot Mar 20 '19 at 3:18
  • $\begingroup$ My initial thought is that it would be odd to use a low-wing for bush work. But I'm wrong, and there's a whole site about it: backcountrypilot.org/forum/bcp-low-wing-17587. My favorite quote from that page is "You don't need big tires, just big b#lls". $\endgroup$ – grumpy1arrival Mar 20 '19 at 20:06
  • $\begingroup$ There is at least one PA-28 on floats as well. It's a goofy looking plane. $\endgroup$ – acpilot Mar 20 '19 at 23:33
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Any time you make a modification to a certificated aircraft you need FAA approval. Even what appear to be minor things, like replacing you sun visors with better ones requires an STC. Putting in shoulder harnesses requires and STC. I could go on forever, but you get the idea.

Putting tundra tires on your Cherokee is a major change. If you look in the parts manual, your Cherokee probably came with 4 ply 6.00x6 tires so to change them you need an STC. You would also need to get an STC for the wheels and brakes. You’d probably need a new nosewheel fork as well.

I have never heard of anyone putting tundra tires on a Cherokee, but stranger things have happened.

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  • $\begingroup$ STC is not the only option, there are also field approvals $\endgroup$ – pericynthion Mar 19 '19 at 23:20
  • $\begingroup$ I think @JScarry is correct. This is not something you could do using a Form 337. You would need a kit that includes a larger nose fork, and possibly longer axles, different brakes, etc. $\endgroup$ – John K Mar 20 '19 at 0:55
  • $\begingroup$ @pericynthion I edited the answer. Technically you are correct that you can modify aircraft with a field approval, but a major modification like this would not qualify. $\endgroup$ – JScarry Mar 20 '19 at 12:48
  • $\begingroup$ Why? 337s are major repairs or alterations. Seems like with the right DAR and enough data, anything can be approved. $\endgroup$ – acpilot Mar 20 '19 at 23:33
  • $\begingroup$ @acpilot I suppose you could put somewhat larger tires on a Cherokee with a field approval but if you are talking about real tundra tires—the ones that people like Trent Palmer and the Flying Cowboys use—I think it would be nearly impossible to get field approval. Maybe someone has done it. If so, I would love to hear how they did it. $\endgroup$ – JScarry Mar 20 '19 at 23:56

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