Alaskan Bushwheel sizes.

[redbowen]

I would like to get some input on the favored Alaskan Bushwheel size for the Patrol. 26" 29" or 31".

[Battson]

First question - what are you going to do with them? Where do you want to land?

No way to answer the question without knowing a lot of detail about that.... Unless you are only going for "ramp appeal"!

[redbowen]

Off airport, river bars, meadows, etc. looking for feedback from Patrol owners that can give input on weight and speed penalties. Obviously bigger is better for landing, but what has the best balance between off airport benifits and speed penalties.

[Battson]

I can't help with the speed question specifically about the patrol, but I can share my experience about off-airport tires.

You can do gravel and grass surfaces quite safely with 8.50s or 26s if you feel comfortable about it, I used to do it on 26s for several years. You can go 90% of places on 26's.

The big bushwheels only buy you a little more access - but a lot more insurance for unseen objects... It all depends how extreme you want to go, how long your average flight is, and whether the airspeed loss is worthwhile. If you only do short local hops mostly, then you might as well go larger if you can afford to.

Grass:
Bushwheels are a disadvantage on wet grass, you have almost no grip for braking or steering. The meadow has to be quite lumpy for the bushwheels to pay off.

Rocks:
- Rocks as big as a softball are OK on 26" tires.
- With 29s you'd be OK to about rock melon sized rocks. This is about as big a rock as you can taxi over for any distance.
- The 31s are a lot wider and can be run softer, so they are good to about watermelon or human head sized rocks if necessary - not something you want to take lightly. If you're landing and coming to a stop on rocks that big, you cant really taxi or push the plane once you stop. The tailwheel won't handle it for very long, you eventually get jammed and stuck, plus it gets bashed. You need to lift the tail and roll forward under power, or have a smooth spot to come to a stop on.

Soft surfaces:
The 31s really come into their own on soft surfaces like sand, mud, and gravel. The extra width and lower pressure stops the mains sinking in. Of course the tail still sinks in sand or gravel if you have any weight on-board. Once the tail sinks, it prevents you doing much taxiing or re-positioning, except from coming to a stop rapidly. Again, you need to lift the tail under power to roll forward, which isn't good because you suck bucket loads of sand / gravel into the prop and sand-blast your wing struts and cowl. This ruins everything pretty quickly.

Self-insurance:
The 31s are good if you come across unexpected holes or lumps, like an unseen rabbit warren or a random big rock. I also know someone who accidentally rolled over a sheep which was laying in his way. I've landed on an unseen concrete block the size of a small yeti cooler and got away with it. Not good though.

Goodyear 26s:
The Goodyear 26s cost us no speed I could notice, got us into 90% of the places we could ever want to land, and still allow you to taxi and land on pavement. We wanted to expand the number of places we go, NEVER need to land on pavement, and only do short flights now. So the 31s make sense. If we were still flying long distance, or EVER need to use tarmac - I would have stuck with the 26 Goodyears.

Speed:
My research into speed loss across a range of aircraft suggested the 29 and 31 tires are both slow, not much difference between them. The 26s are much less drag.

Pavement:
All the Alaskan Bushwheels will be destroyed quickly if you use sealed surfaces very much. In that case, the Goodyears are the best option.
I have seen the 8.50 Desser tires, they are a LOT smaller than the Goodyears. I would not recommend them.

[schu]

+1
Battson is dead on.

I have 26" goodyears on my 170, they work good and handle pavement well. The bushwheels are a lot softer and soak up unforeseen circumstances, but don't hold up to pavement at all. So if you aren't doing bush exclusive stuff, they probably aren't worth it, but if you are, they are amazing.

[Battson]

This from Rob over at the Backcountry Pilots forum - good info, Rob would know....

The sidewall of the 29" ABW is substantially stiffer than the sidewall of a 31. This difference makes the 29 stand more erect than a 31 at the same air pressures under the same A/C. On a lighter airframe, this translates to a stiffer ride. On a more appropriate weighted airframe for the 29 ABW (such as a C180) the stiffer sidewall may actually favor your flying style / mission. Anyone who has gone from 26" goodyears to any flavor of appropriately aired bushwheel should understand this concept. Mind you, very few people I have witnessed flying ABW's run them at optimal pressures for the conditions. Most shove them out of a paved airstrip hangar, and then head to the beach or boulder pile. I am frequently guilty (but cognizant) of this.

[Helidesigner]

I am looking into going from Goodyear 8.50x6 to the Goodyear 26 in smooth tires. I plan on flying in Idaho and Maine the next few summers but there will be a mix of grass, gravel, and pavement. I would like some extra flotation for soft and/or lumpy grass fields. Do I have to get tubeless hubs? I understand you can get an innertube for the 26 in tires but is that a good idea?

[zkelley2]

For that use, there is beyond no need to run more than the 8.50. Anything more is drag and vanity.

There's not a single thing anyone would consider a strip that you can land on that a 8.00 won't work. Past that we're talking about making places to land out of nothing. If you're not doing that, bushwheels are not needed. Unless you need to feel like a youtube star.

[AKKen07]

I’ve got a bunch of time in a Citabria on those 26s with tubes. Mostly off pavement and a fair amount off field. Those things are bullet proof. They won’t get you low psi Ak bushwheel floatation, but you’d be doing some pretty intense flying to need more - IMO.

[jaredyates]

I ran them with tubes. Just for extra redundancy I drilled through the hubcap holes, tapped the threads all the way through, and installed the hub cap with pointy screws that protruded a little into the tire bead.

[schu]

The thing that makes bushwheels able to work so well is the ability to air them down to the point where they can roll over uneven ground without beating up the airframe. Many pilots will run them down in the 6psi range or even less. The reason they can do this and the GY26 can't is because bushwheels don't have an inner tube as the tube and tire are one piece with the schrader valve mounted on the side of the tire. If the tire slips on the wheel there isn't a stem to shear.

With a GY26 and a tube, you would really want at least 10psi in them to make sure you don't shear a stem, that said, the GY26 is actually a tubeless tire, so you could in theory get a tubeless wheel, but the only ones I know of are the grove 10" wheels, which allow you to run a different tubeless tire called the desser.

I have a set of 31" Desser tires with grove 10" wheels on hand. I should be able to air them down a bit for really soft field ops and not worry about wheel slip, but, the side walls aren't as flexible as a real bushwheel. I feel this is a reasonable tradeoff for pavement durability.

[m.mooney]

I’ve got the 31 Desser and grove 10” setup for my Patrol. Because of a few big rock gravel bars that I frequent, I switched to the 35” ABW on the grove 10” wheel. My plan was to run the dessers in the winter and the 35s the rest of the year, I bought a second set of wheels to make it a quick change. Full disclosure, the 35s have yet to come off the airplane, they’re phenomenal and undoubtedly provide the largest safety margin for the rough stuff. I ran the Dessers tubeless at 11 psi without lockers but I never really pushed the envelope because of the valve stem shearing possibility. If I wouldn’t have gone with the 35s, I was going to do the bead lockers. They are awesome tires which I will eventually get around to swapping back on, just not anytime soon. I think the Desser 31/Grove combo would be perfect on the BH5. With the 35s, I frequently find myself landing in spots that I would’ve never considered before.

[schu]

Huh? You ran the dessers tubeless at 11psi, and was concerned about the valve stem shearing? How on earth would you shear the valve? It’s just an o-ring into the wheel? It doesn’t connect to the tire at all.

[m.mooney]

Yeah, my bad, I was worried about breaking the bead. Since I don’t have that threat anymore, at least not as much, I’d forgotten about the details.

[Battson]

Here's a brief overview of my thoughts on the subject:
https://backcountrypilot.org/knowled...188-tire-guide

We ran Goodyear 26's for many hundreds of hours on all surfaces. I used inner tubes and bead lockers and Jared describes above. Here is how to do it:
https://bearhawkforums.com/forum/too...th-inner-tubes

Would I do it again?

If you are going to spend money on tubeless hubs, you are better to spend it buying AWBs for your existing hubs - unless you do a lot of pavement work. The tubes are a weak point, however that risk is completely managed with the bead lockers.

The Goodyears will give you the floatation on soft stuff and the reduced rolling resistance over obstacles. They do very little to protect the airframe from jolts and bangs though. They do still kick up rocks too.

The ABWs run at the right pressure will roll over rocks without throwing them up in the air. They only throw rocks at the start of the touchdown when the wheels have to spin up.

Overall, the only reasons to use a Goodyear tire on an off-airport machine are 1) regular pavement visits, and 2) price point. They are just as capable, however they are a lot (read a LOT) harder on your airframe, compared to the 26" ABW.

[schu]

If you are going to spend money on tubeless hubs, you are better to spend it buying AWBs for your existing hubs - unless you do a lot of pavement work. The tubes are a weak point, however that risk is completely managed with the bead lockers.

I’ll be operating off of pavement a lot. My local airport is not at all interested in having a grass strip. I could possibly land before the runway, but it’s only a matter of time before it’s reported, then I’ll have to deal with nosepickers.

In my mind the desser setup is ideal for this. It’s light, the tires are half the price and last twice as long, no tube to deal with, if the tire slips it doesn’t matter, better brakes, etc. While it’s not quite a bush wheel, it’s waaaaay closer than the Goodyear.

[m.mooney]

I anticipated frequent pavement ops, which was my reason for going with the Desser 31s but I do have grass at my airport and have only landed on pavement a couple of times with the ABW 35s while on the road. If I didn’t have grass at my home strip, I wouldn’t have gone to the 35s and would agree that the Dessers are the best option, much better than GY 26s, in my opinion. The Dessers are stout as hell, I think you could run them for a very long time. Don’t forget about the advantages of the 10” wheel with 7.5” brake discs.

[whee]

A friend of mine has every size of Bushwheel for his BH. He started with 35s, then 29s, then 31s than back to 29s. He felt like 29s were the best compromise for a plane that goes off-airport and is used to commute. He said there is a measurable speed loss between 29s and 31s. He ‘retreads’ his Bushwheels ever other year using a rubber compound and says he has no problem with frequent pavement operations.

In my option almost no one needs anything bigger than 8.50s. There isn’t a place in the Idaho backcountry that you can’t go on 8.50s. However, and my friend mentioned above agrees, the most significant reason to put big tires on a BH is to increase prop clearance. My prop is literally being destroyed by rock damage even on paved runways. My prop is very long but even my friend with an 84” prop said prop damage was an issue for him until he switched to big tires.

I would love to have a set of 31” Desser tires but the cost is significant. I need to not be so short sighted and spend the money anyway. Before too long my prop will be ruined and it’s replacement will make tires look cheap.

[whee]

Zkelley, a composite prop would wreck my CG and make the airplane useless to me. I need every bit of that 72lb prop and if my engine was rated for a heavier prop I’d consider buy it. Of course a 540 or 470 would fix that issue. But the stump pulling power of my prop would be missed if I go to a shorter prop.

[whee]

Gerhard, I looked at 900s and I think 950s and they were big enough to make a difference in my situation.

[Battson]

OOOHHHH NO to the composite prop, those are even more delicate!! Most stones hit the aft face of the blade, few hit the leading edge. The aft face of a carbon blade just cannot take the hits. One good hit will write off the blade.

[m.mooney]

In my option almost no one needs anything bigger than 8.50s. There isn’t a place in the Idaho backcountry that you can’t go on 8.50s

If it’s an airstrip, which all of those are, I totally agree, 850s are great. If it’s off airport, it’s a whole different discussion, the bigger the better. 31s are awesome but I went with 35s because I already had Grove 10” wheels and brakes for the Dessers. Only one Bushwheel option with 10” wheels and that’s 35s. They’re amazing.

[whee]

If it’s an airstrip, which all of those are, I totally agree, 850s are great. If it’s off airport, it’s a whole different discussion, the bigger the better. 31s are awesome but I went with 35s because I already had Grove 10” wheels and brakes for the Dessers. Only one Bushwheel option with 10” wheels and that’s 35s. They’re amazing.

I agree, true off-airport is a totally different discussion and I would go as big as possible, so 35s. My friend puts on the 35s when he knows he is going out to play.

I hate to be that guy but if you ever decide the 31” Desser tires are excess to your needs I’d be interested in a shot at buying them.