hotrod150 wrote:

8GCBC wrote:Gross_weight / (overall_tire_height x tire_width) = big_tire factor...........
#1 Scout with a Gross of 2150 LBS fitted with 31136.R (31") tires would have a "big _tire_factor" of (5.3)
Example 2150 / (31 x 13 ) = (5.3) big_tire_factor
#2 Scout with a Gross of 2150 LBS fitted with 8.5 tires would have a "big _tire_factor" of (42.1)
Example 2150 / (8.5 x 6 ) = (42.1) big_tire_factor
..........

Your idea's good, but you're comparing apples to oranges. You need a big-ass set of calipers to measure the actual OD & width of the mounted tire, so you can use actual dimensions, not arbitrary numbers (such as the 8.5 on airplane #2) from the size designation. You also need to extrapolate tire contact area somehow by using tire pressure and weight of airplane. Contact area and weight per sq inch would give an indication of how much flotation they'd provide, but you'd also need to factor in diameter and it's effect on being able to roll over obstacles. A small diameter fat tire might be better in sand while a large diameter skinny tire might be better in rocks, In short, I don't think this is something that can effectively be compared using math.
I use math to compare airplane performance potential by comparing a combination of power loading (weight / horsepower) and wing loading (weight / wing area). This is apples to apples but can't take into account different airfoils, liftier flaps, etc or pilot technique and skill.

What sets do you fly?.

Looking at the front-runners, does anyone know what height and width 8.50's and 26" Goodyears are (I bet they aren't 26") if you put a tape measure next to them?

Other than one being treaded, is there really that much difference in terms of ability to deal with stones/gravel? How about riding through rough surfaces or staying atop a not-so-firm sandy surface?

Ran 8.50X6 on the 180 till they went bald, went to 29" bushwheels after that. Not only do the 8.50's throw gravel every which way, they offer little if any shock absorption in comparison. Have over 500 hours on both kinds and am done with 8.50's. If your goin in and out of mildy rough stuff often, IMO bushwheels will save your equipment ALOT of wear and tear. The 8.50's performed poorly in the gravel beds and sand, even smooth ones (footprint). Just got a pair of 31" ABW to replace the 29's.

On the Super Cub the 8.50's don't seem to throw gravel anywhere near as bad as the 180, thinkin its a weight thing. Just as with the 180 I have been pretty dissapointed with the 8.50's. For now my Dad is learning to fly in it but got a set of 31's sittin in the hangar waitin to go on when he's ready to start flyin to the ranch. It's been kinda funny flyin the cub into places I thought were pretty smooth in the 180, actually been shocked how rough some spots are with the 8.50's on the cub that are gravy with the 29's on the 180. It's not that you can't get it done with the 8.50X6 it's are you willing to beat the crap out of your plane day in and out.

Bushwheels are great and if your mission involves lots of off airport they are well worth consideration. 8.50's are just a glorified hockey puck's IMO and might as well stick with smaller tires if not goin to ABW. The 8.50X10 or 29X10 are a good compromise for folks that have to hit pavement a lot, still don't give much more shock absorption though.

Also, I get the bushwheels with extra rubber in the wear spots (for just a little more $$$) and have found that they wear much better on pavement. Not sure if airframes alaska (who supposedly bought out ABW) will continue to offer the custom bushwheels, sure hope so.

Battson wrote:Other than one being treaded, is there really that much difference in terms of ability to deal with stones/gravel? How about riding through rough surfaces or staying atop a not-so-firm sandy surface?

I don't have the 8.50's any longer so can't put a tape to them. I can measure the 26" Goodyears next time I'm at the airport if no one else posts before.

Here is a photo of the three I've had on the 185. You can get a sense of the floatation difference between the sizes. The 26" Goodyear is made from stout rubber so would not have the same floatation as the 26" ABW. Since the ABW is a softer rubber it deforms more at lower tire pressures which increases its overall footprint.

But the 26" Goodyears wear, as others have said before me, "like iron". And are substantially less expensive. They handle both hard and soft surfaces very well. An excellent tire in my opinion if you'll be on both surfaces.

On the 185 I experienced no "noticeable" difference in top speed between the 8.50's and the 26" Goodyears. That might not be the same for every plane.

I measured the height of an 8.50 x 6.00 tire and it came out to be 21". I had measured them when they weren't on the airplane, and I never did measure the width.

-Nate

Hey shorton,
I couldn't respond either. Here' why:
You have to log in with your user name and password.
Even tho I click the "remember me" box, I seem to get "forgotten"
I have to log back in at least each month.
Sam

I was looking at the 26" good years and they came out to be between 22/23" tall based on inflation. I was seeing around 10" in width which was the thing i was a little worried about going on to sand. I'm surprised to see how few ABW 26/29's people are running. I came out to a big tire factor of 5.3 on my Rebel with the 26's based on the formula. They seem great and suit the plane well..........but I kind of wish I got the 29's...........or 31s.......or......

Next time.

Barnstormer wrote:

Battson wrote:Other than one being treaded, is there really that much difference in terms of ability to deal with stones/gravel? How about riding through rough surfaces or staying atop a not-so-firm sandy surface?

I don't have the 8.50's any longer so can't put a tape to them. I can measure the 26" Goodyears next time I'm at the airport if no one else posts before.

Here is a photo of the three I've had on the 185. You can get a sense of the floatation difference between the sizes. The 26" Goodyear is made from stout rubber so would not have the same floatation as the 26" ABW. Since the ABW is a softer rubber it deforms more at lower tire pressures which increases its overall footprint.

But the 26" Goodyears wear, as others have said before me, "like iron". And are substantially less expensive. They handle both hard and soft surfaces very well. An excellent tire in my opinion if you'll be on both surfaces.

On the 185 I experienced no "noticeable" difference in top speed between the 8.50's and the 26" Goodyears. That might not be the same for every plane.

I've been wondering what a side to side comparison would be.. Thanks

TheRebeler wrote: I'm surprised to see how few ABW 26/29's people are running. .

Me too!

Thanks for the info guys, at this stage it'll be a toss-up between the 26"s GYs and the 29"ABW one the 8's are well worn through time on type on tarmac...

Skalywag wrote:Ran 8.50X6 on the 180 till they went bald, went to 29" bushwheels after that. Not only do the 8.50's throw gravel every which way, they offer little if any shock absorption in comparison. Have over 500 hours on both kinds and am done with 8.50's. If your goin in and out of mildy rough stuff often, IMO bushwheels will save your equipment ALOT of wear and tear. The 8.50's performed poorly in the gravel beds and sand, even smooth ones (footprint). Just got a pair of 31" ABW to replace the 29's.

On the Super Cub the 8.50's don't seem to throw gravel anywhere near as bad as the 180, thinkin its a weight thing. Just as with the 180 I have been pretty dissapointed with the 8.50's. For now my Dad is learning to fly in it but got a set of 31's sittin in the hangar waitin to go on when he's ready to start flyin to the ranch. It's been kinda funny flyin the cub into places I thought were pretty smooth in the 180, actually been shocked how rough some spots are with the 8.50's on the cub that are gravy with the 29's on the 180. It's not that you can't get it done with the 8.50X6 it's are you willing to beat the crap out of your plane day in and out.

Bushwheels are great and if your mission involves lots of off airport they are well worth consideration. 8.50's are just a glorified hockey puck's IMO and might as well stick with smaller tires if not goin to ABW. The 8.50X10 or 29X10 are a good compromise for folks that have to hit pavement a lot, still don't give much more shock absorption though.

Also, I get the bushwheels with extra rubber in the wear spots (for just a little more $$$) and have found that they wear much better on pavement. Not sure if airframes alaska (who supposedly bought out ABW) will continue to offer the custom bushwheels, sure hope so.

Have you ever flow a plane with 8.00? That's what I have right now and I'm contemplating if I should go to 8.50's or 26'' bushwheels when it's time to replace. I'll be doing hard surface landings every now and then, so I want to be sure I'm not going to wear them down too quickly.

ATXCitab wrote:[I'm contemplating if I should go to 8.50's or 26'' bushwheels when it's time to replace.

You are welcome to try my 26" Goodyears to see how the Citabria does with that tire.

Barnstormer wrote:

ATXCitab wrote:[I'm contemplating if I should go to 8.50's or 26'' bushwheels when it's time to replace.

You are welcome to try my 26" Goodyears to see how the Citabria does with that tire.

Atx, I went from 8.00s to 31"ABWs with a babybushwheel on my GCBC. I'd do it 100 times again. The angle of attack is great, and man its soft landing on those pillows. I land on pavememt every now and again, and just land as slow as possible and don't turn sharp. Haven't noticed any crazy wear on them yet. IMHO, if your going with 29s you might as well just go 31s...

David

Get the biggest tires your wife says you can afford...if that doesn't work out for you pull the Mountianmatt trick.

So all you guys running 8.50s......................would you use 31s if $$$$$ were no object???????

OregonMaule wrote:So all you guys running 8.50s......................would you use 31s if $$$$$ were no object???????

No. It depends on the mission. I have 8.50 on now. Good for pavement trips, with a little less gas and rubber left behind.

There is no perfect one size fits all MLG tire from my limited experience.

I may have missed it posted here but the rolling diameter plays an important part of how big of things you can roll over with out breaking something. I know of a person that decided to put to the test, how big was to big on a 35", he found logs that were laying out on the ground and preceded to see how big of log he could roll over. I heard that 16" was doable and that 18" bent the lower longeron above the gear attach point. There are going to be lots of variables to the test, how much air pressure in the tire, how much does your aircraft weigh in the current configuration, how fast are you landing at etc. etc. You have to learn what the tires can do by doing and then use common sense. It does not make sense to try and roll over an 18" log if a mile a way you can land on a flat patch of sand.

The 35" tire I can run at 2-3 psi and land on really ruff stuff without breaking anything if I want to, the 31" tire you can run at 4-5 psi and land on most of what a 35" can but you will probably be inflicting damage that is unseen. I know of a guy that landed really ruff stuff on 31" tires and over time had to re-bush his gear, gear fittings, broken cabane vee attach points, now he is on 35" (there is a reason ). The 35" ABW at low pressure is a whole different tire over a 31" ABW at low pressure.

For me the 35" is a good choice, would a 31" work most the time, probably. Would I want to fly around on an 8:50, no way, I would quit flying if that is all I had. Flying from airport to airport is boring, if I can not break it up by landing off airport I would probably quit flying.

The speed penalty is the biggest downside for me not the cost of the tire. The tires last forever if you use them for what they are built for, even landing on pavement they should go a long time based on the circumference of the tire. The 35" are more drag then straight floats, they cost me 7or 8 mph over a 31" and I think the 31" cost me 10 mph over a 26" Goodyear but that was a long time ago and my memory is foggy. I am still flying the first pair of 35" ABW ever made, Bill Duncan delivered them to me in 2005. They have thousands of off airport landings and even a bunch of pavement time from when I have to use the dang asphalt. I can only guess at how much wear I have left but based on a few deep gouge marks I would say another 10 years of screwing around.

Thanks for posting Greg - interesting to hear your viewpoint, given how much true 'off airport' flying you're doing. Sounds like the 35's really make sense in that case.

I can't really answer the pole, the only off airport landings I've done to date were on skis, and I didn't see a 60.00x12 option.

I landed on a lot of grass, dirt and gravel airstrips with 6.00x6 mains and 5.00x5 nose in my old Cessna 150. And I've done the same using 8.00x6 4 ply mains on the Challenger. When the Patrol is finished I plan to start with 8.50's and go from there.

You guys with 35" tires landing on big rocks, and soft sand are impressive as all get out, and I own a couple of cub porn videos myself, but that's high risk flying and I'm not willing to bust up my plane to make a cool video. Smaller tires keep me from landing where I shouldn't.

My favorites are my 35s. Most of the time I have my 29x11x10 AirHawks on.

poll is missing 29" airstreaks - you got 26 but no 29