Larger Tires for a 170B?

[JackHart]

All,
Thinking of putting a larger set of tires on my 1952, 170B to be able to do some dirt strips in the Cascades and in Idaho. Does anyone have specific experience putting on a larger tires? Is a STC needed, 337, any ideas on specific make and model, size of tire?

Thanks for the insight,
Jack
2354D

[Jr.CubBuilder]

800x6 no STC need it's in the TCDs, just make the changes to the equipment list and update your weight and balance for the weight of the bigger tires and tubes. I like my Goodyears so far better than my AirTracs but it's apples to apples, I think the goodyears are better rubber.

[N3243A]

Jack,

How big do you want to go? In sizes larger than 8:50 x 6 you have two STC'd options, Alaska Bushwheels and Alaska Tundra tires. Be prepared to write big checks...........

Bruce

http://www.akbushwheel.com/PRICELIST31008.html
http://www.alaskatundratires.com/maingear.html

[JackHart]

Gentleman,
Thanks for the insight. I have 800x6 on there now, and would like to go to the next size up, or maybe two sizes up.

Has anyone put on bigger tires and how did it work?

Thanks again,
Jack
2354D

[Lucky]

I have the 8:50 x6's on my 170B...it's what it came with when I bought it and when it came time to change tires, that's what I stayed with. I've heard several people opine that if you need anything larger than that, you need a different plane, as the spring gear on the Cessna is too bouncy for landing on surfaces requiring larger tires. I don't have enough rough-surface landing experience to know one way or another, but the price of bushwheels alone is enough to make me quit investigating. The larger tires seem to be a lot grabbier on pavement. They are also about 50% more expensive and significantly heavier than 8:00's.

Two issues people have raised with the 8:50's: Some break calipers seem to dig into the sidewall if you deform the tire too much on a hard landing...it's never happened to me, but apparently it can be an issue depending on how you're set up. I've also heard that you need a field approval for the 8:50's...maybe you do. I think you can get your nuts wrapped up into an endless knot trying to make a plane paper-perfect, and sometimes it's a hell of a lot easier to beg for forgiveness than ask for permission. For those that disagree, that's fine, but I don't care that much.

All in all I like the tires. I've heard from a good source that the Goodyear's are a fair amount larger than the McCurry's, and that they last a lot longer. I have the McCurry's, as that's what the shop had in stock.

[N3243A]

I have tried both the Alaska Tundra Tires (formerly Gar Aero) in the 8:50x10 size and the Alaska Bushwheel in the 26"x12 size. The Alaska tundra tire requires that you glue an adaptor ring to your standard 6" cleveland wheel halves thereby making them usable only for the 10" wide tires. The resulting larger wheel then accepts the standard 8:50x10 tire and tubes. The Alaska Bushwheel is an expensive rubber donut that goes right on a standard 6" cleveland wheel and requires no inner tube. The Bushwheel is a sealed bladder tire that can be run at lower pressures. Because it has no inner tube, it can spin on the wheel and not be in any danger of shearing off an inflation stem like standard tires and tubes, though they should be inflated to no less than 8 PSI. Each type has its advantages and disadvantages, depends on your needs. The Alaska Tundra Tire requires that you buy a dedicated set of wheels to mount your adaptor rings to but the tires are much cheaper to purhcase and will last longer. The Alaska Bushwheel tires are expensive but provide much more shock absorption in larger rocks and rough terrain because their sidewall is higher and is designed to flex more than a standard aviation 8:50x10 tire. Of the two I prefer the Bushwheel for this reason. If your intended landing areas are relatively smooth but are soft and consist of sand and/or mud, both tires work about the same.

Also both tire types will either require or "strongly recommed" using the steel C-180/185 axles and the cleveland wheel kit 199-62 for clearance issues. This wheel kit is a double puck heavy duty brake system.

Bruce

[Chris Christensen]

First opinion is that if you have a stock 170, then the 800 x 6s are all you should ever need.

I have flown in ID Backcountry for several years now, and there are no strips, that I recall, that NEEDED larger tires.
Most of them are relatively "smooth", the real problem comes with density alt.

You will need horsepower more than big tires.
Any of the "Fabulous Few" that are critical, would be TOO SHORT; for a stock 170 to get out of.

Second opinion is that now that I do have Alaska Bushweels 26" tires, I love em.
Bought a second set of wheels and 800x6 Dresser Re-treads with the thought to saving my ABW rubber, but found it not to be cost effective with all the labor and cost to switch back and forth. Will just buy a back up set of ABWs. someday WUP !

I, and another stickler for staying inside the FAA rules, searched for an STC to use 850s on 170s and could NOT fine one. Chased every rumor we came accross.

There is a fella in Canada that DOES have an STC for putting 180/185 legs on a 170.
Then Alask Bushweels has the STC for upgrading the brakes to DOUBLE piston / pucks system and the Alaskan Bushwheels.

PS: I actually have a spare set of wheels forward 185 landing gear I could sell.
I went to 180 gear to save a bit of weight. The 185 gear is 1/16th inch thicker.
ALSO strongly support the use of the P-PONK upgrade. Saved My plane once, and that was enough.

[JackHart]

Gentleman,
Thanks again for your insight with this issue. I always appreciate someone with knowledge and experience. I look forward to having a bit bigger tire on my 170B.
I do have a 180hp engine and look forward to landing on some longer dirt / mountain strips.

Thanks again for the help,
Jack
2354D

[hilltop170]

Jack-
Alaska Bushwheels has another new option that has just come out and is approved on all 170s. They have recieved FAA TSO and STC approval for a one-piece 10" wheel that DOES NOT require glue or adapters and weighs in at 12lbs with the brake disc. Depending on how much bigger tire you want, you can either use AirHawk 29" x 11/10 or AirTrack 8:50 x 10" tires & tubes. The total weight with the 29" AirHawk is 45lbs each. Double-puck heavy duty brakes are required if you don't already have them.

(See STC# SA01765SE)

ABI-1010 -- $1650.00/pair with brake disks included

29" x 11/10 AirHawk (Buffed) -- $ 800.00/pair
AirTrack 8:50 x 10" tires & tubes -- $ 500.00/pair

I have been running 8:50 x 10" tires (with 10" wheel adapters on 6" Cleveland wheels) on my C-180 since 1984 and think they are the perfect size, all things considered, for the type of flying I do in Alaska; beaches, gravel bars, and tundra. I think 29" x 11/10 tires are too big and too grabby for Cessnas. I know guys who have torn out gear boxes with them. 8:50 x 10" tires fly just the same as 8:50 x 6" and give much greater floatation without the speed penalty of 29" x 11/10s.

The new Alaska Bushwheels one-piece 10" wheel conversion looks like the best deal to me. It will cost $2150 to buy the wheels and tires and probably another $600 if you need the brake upgrade. But, replacement tires and tubes are much cheaper down the road and the 8:50 x 10" tires last a long time.

Having an STC'd set-up is much cleaner and no B.S. from the feds.

[JackHart]

Richard,
Thanks for the insight and letting me know how you handled it. It sounds like your set-up is perfect for what I want to do.

Appreciate your time,
Jack
2354D

[flat country pilot]

Richard,

Does the Alaska Bushwheels 8:50 x 10 STC cover the 170?

Bill

[Lucky]

Asside from the STC, is there any advantage to the 8:50x10 verses the 8:50x6? If the outside dimensions of the tires are the same, it seems like the larger wheel would reduce the ability of the tire to cushion the bumps.

[hilltop170]

Bill-
All C-170s are included in the STC.

Lucky-
Measuring the tires, the 8.50-6 outside diameter is about 21", the 8.50-10 outside diameter is about 24"and much wider (I don't know how much). It makes a big difference. Plus, the brake caliper is inside the wheel where it is out of the airflow and protected from being able to rub on the tire.

8.50-10 vs. 8.50-6

[Lucky]

Hilltop,
That's quite a difference in size. I agree that spending some money up front for the larger wheels, which will then allow you to put on less expensive tires, makes sense for some people...especially those of us who have to do a lot of our flying off of pavement

[hilltop170]

About 3/4 of my flying is on pavement but the off-airport part is evenly spaced thru the year so I can't effectively put big tires on when I want to land on a beach. So the 8.50-10 wheel/tire combination is the best answer for me. Large enough footprint for soft surface and easy to handle on pavement.

The picture was taken yesterday at the 2008 Valdez Fly-in Poker Run beach landing at Hook Point on Hinchinbrook Island on the Gulf of Alaska side. There were probably 20 planes of all sorts from C-150s to a Navion. That beach is hard enough for just about anything to land on, but most are not that good.