31" bush tires on cessna 170b

[jon s blocker]

Seems like we are all learning as we go . I have double puck Cleveland wheels and brakes, and the 850s which were all done on FAs, along with several other FAs and STCs on my B model.

[Francis Cahoon]

jon, does your B have any mods that decrease takeoff distance and landing distance?

[jon s blocker]

Francis,
I have a Lycoming 0360 narrow deck with a Hartzell 80" prop. It makes the plane a good performer, but the lighter the better. Mine is heavy, with several other mods. Look into a Sportsman STOL kit, Seems to give better slow flight characteristics, and probably let you land a little shorter, but not take off much shorter. Weight and Power are what you should concentrate on. A 170 will already get into places you probably can't get out of.

[Francis Cahoon]

thanks jon, sounds like you have a great plane. if you ever get up here to mt. give me a call.

[jon s blocker]

I will be trying to go to Johnson Creek and Missouri Breaks this spring. Will try to contact you if I get to go. Jon

[Francis Cahoon]

Sounds great jon. If you like hunting and fishing outdoor stuff, there is a lot of stuff to do here. I use to be a hunting and fishing guide so if you need something let me know, Thanks again for the info about ice. F. Cahoon

[Blue4]

I'd like to point out the biggest shocker for me going from what I call training wheels -- 8.00s -- to big wheels (29 inch bushwheels).

My little 8.00s, by the way, were the biggest tires at the convention this summer in Kentucky (I think I'm the only one who had them). And I only brought them down from Alaska because I would have had to purchase 6.00s and, after a cost comparison, found that they weren't worth the cost for that one (very long) trip from Alaska to Kentucky and back.

In any case, the shocker was rolling resistance. As VERY objectively (ladies and gentlemen, please note that the captain has illuminated the sarcasm sign) measured by ground handling with little wheels and big wheels, I've been absolutely amazed at how much more rolling resistance the 29s give as compared to the little wheels. On tiny tires (8.00s), I can easily ground handle the airplane into my hangar myself. On the 29s, I can barely do the same thing.

On bushwheels, this increase in friction probably affects short field takeoff performance more than the increase in angle of attack. On landing, brake performance is decreased due to the larger diameter of the tires, but this may be offset by the increase in rolling resistance.

The bottom line for takeoff/landing performance is that big tires are probably a wash.
-Scott

[Bruce Fenstermacher]

Good point Scott.

[johneeb]

I'd like to point out the biggest shocker for me going from what I call training wheels -- 8.00s -- to big wheels (29 inch bushwheels).

...................................In any case, the shocker was rolling resistance. As VERY objectively (ladies and gentlemen, please note that the captain has illuminated the sarcasm sign) measured by ground handling with little wheels and big wheels, I've been absolutely amazed at how much more rolling resistance the 29s give as compared to the little wheels. On tiny tires (8.00s), I can easily ground handle the airplane into my hangar myself. On the 29s, I can barely do the same thing.

...........................................
-Scott

Scott,
It sounds like you may have a little problem with wheel toe in or out that would be more noticeable with bigger tires.

[Blue4]

Excellent thinking, John! We actually checked for that -- and you were right, I did need a little adjustment.

But even after that, it really does take a lot more oomph (a Minnesota technical measure of force measured in post-movement uffdas) to move the airplane on the large-footprint soft rubber bushwheel tires. A subjective measure, but its definitely there.

-Scott

[Francis Cahoon]

Thank you guys for the input, good info, experience in my opinion is always an important factor to consider. At the present time the paper work is near completion, waiting for one more piece of documentation to enable me to put goodyear 26" tundra tires on my old girl. Later after I win the lottery, and experience the pros and cons of said tire, I might try larger. the FAA guys have been great. Thanks to all that have responded thus far. Francis Cahoon

[blueldr]

Francis Cahoon,
As a matter of curiousity, where do you live and where are you planning to fly your C-170 so that you feel you're going to need those great big tires?

[dunlaps3]

I have my 170B on 31" tires for a few years now. They are better than skis in the winter. Also , a good safety item if a forced landing occurred.
Once , I put my little 8.50's back on and my plane lost all it's character. Back off they came. Whew ! 31" is the only one for me. Andrew

[Francis Cahoon]

blueldr, I hope this answers any questions you may have. I live on the Flathead Indian Reservation, in north western Montana. I am a member of The Confederated Salish and Kootenai Tribes. The area varies from 12000 ft. mountains to around 2500 ft. valley floors. One major fresh water lake 28 miles long (Flathead Lake) with the Flathead River flowing to the west, with sand and gravel bars. There are some farm land, some grazing, some wilderness, and some rolling hill land. All potential landing spots. Our mountains (The Mission Mountains) are part of the Rocky Mountain chain, which led north up to Glacier National Park. My intentions are to possibly work for my tribe in one of the following jobs which are currently held by nontribal members. Such as aireial surveillance, winter and spring big game counts, bald eagle counts, swan counts, fire suppression, aireial gunning for stock predation, scenic flights, etc. In my opinion, there are lots of stuff for me to do with this type of plane and mods. The bigger tires I hope will allow me more landing spots, etc. I store my plane out side on a grass strip, use a little pavement when I fill up with fuel. I log and fight wildland fires for a living, so my schedule is pretty flexible. Hoping to head to Alaska with my Family for some hunting and fishing this summer and fall, I plan on flying from here. Thanks for the question. Francis Cahoon

[Francis Cahoon]

dunlaps3, Thanks for you input. I really enjoy hearing from people that have some of the mods. I have or am thinking about getting. I hope I can upgrade to the bigger tires once I see how I do with the 26''. You mentioned that you use the bigger tires in the snow correct? If you have some time would it bother you to tell me your opinion on snow depth, consistently, any thing that would help me determine if a landing and take off would be achievable. I know all things change, so it would only be your opinion, but your experience is greater than mine at the present time. My phone number is 4Osix 261 sevenO46 if you would rather communicate that way. Thank you Francis Cahoon