https://backcountrypilot.org/knowledge- ... tire-guide

Battson did an awesome job writing this up for us. It's probably a little rudimentary for most of our members here who've been paying attention to tires on the market for years, but my hope is that it will provide a good intro to what's out there for tire and wheel options for the newbies.

Any feedback or corrections are welcome. Leave them here or in the article comments.

Thanks.

This is great intel, I've been pondering oversized shoes for sometime and this was very helpful.

Thank,

Mapleflt

Ditto, this is fantastic info!

Very nice job. Just what I needed to start my search!

Very good article. There are many avenues and basis of eligibility issues with all airplane models, the field approvals, and STC options out there. Not sure how anyone could explain it all, but this is a great place to start.

I like the idea of big tires, and enjoy reading about them, but summers for me are on amphibs. Winter, 6:00-6 tires take me all the places I want to go, quickly.

That sums it up nicely, good job!

I'm a pretty rudimentary guy. All good info. Well written and informative.

If anyone spots any bad data or inaccuracies, please chime in. The knowledge base is a living thing and I will implement additions/edits/etc.

Very informative and well written! I applaud Jon for tackling this and putting it together.

There is one thing that isn't mentioned that may be note worthy to some, larger tires will decrease ones climb rate. This was very noticeable when I had my C180A on 31s taking off at 9500 and climbing to 14000+ to cross passes. (I'm not sure if this is as noticeable at sea level.)

MM

Woah I got two pictures in it... finally I'm famous.

One thing I noticed is that the diagram (which is awesome by the way) shows the Desser 850's being slightly bigger than Goodyear 850's. I think this may be backwards in reality. However, your diagram also says "by stated diameter" so technically you're correct.

An 8.50x10 seems like a decently popular choice that is left out.

Overall, its a good looking (and reading) article.

-asa

Two questions:

1) Why are 8.5x10's not referred to as 21's? Why is it that on the smaller end of the spectrum things are labeled using one nomenclature and at the other end, a different one?

2) Why, in this guide, is the diameter of the tire referred to as the height instead of the diameter? Is that how things are normally spec'ed out?

rw2 wrote:Two questions:

1) Why are 8.5x10's not referred to as 21's? Why is it that on the smaller end of the spectrum things are labeled using one nomenclature and at the other end, a different one?

2) Why, in this guide, is the diameter of the tire referred to as the height instead of the diameter? Is that how things are normally spec'ed out?

Try not to be so logical / sensible

Both good questions,

First one, that is just how the tires are labelled on the side of the tire. Probably has historical reasons around it, I've no idea what.

Second one, no good reason. There was so much more to cover in this article than I originally expected, it's still got room left to improve.

asa wrote:Woah I got two pictures in it... finally I'm famous.

One thing I noticed is that the diagram (which is awesome by the way) shows the Desser 850's being slightly bigger than Goodyear 850's. I think this may be backwards in reality. However, your diagram also says "by stated diameter" so technically you're correct.

An 8.50x10 seems like a decently popular choice that is left out.

Overall, its a good looking (and reading) article.

-asa

Easy to correct and to extend with more models.

There's a lot of confusion around the sizing of the models in that zone. As best I can tell:

Goodyear 8.50x6: 21" ida
Desser 8.50x6: 22" dia
Goodyear 26x6: 23.5" dia.

rw2 wrote:Two questions:

1) Why are 8.5x10's not referred to as 21's? Why is it that on the smaller end of the spectrum things are labeled using one nomenclature and at the other end, a different one?

2) Why, in this guide, is the diameter of the tire referred to as the height instead of the diameter? Is that how things are normally spec'ed out?

1. I suspect that tires, like many things, suffer from many cooks (mfrs) in the kitchen and naming standards are whatever they want. If 8.00 and 8.50 were specs for width, but their diameter happened to increase proportionally, that's just how it is. I imagine later on it became obvious that diameter was a better descriptor for what people value in a tire for light aircraft.

2. Is it confusing to have those two terms be interchangeable? A mounted tire's diameter is essentially also its height, unless you want to factor in compression under weight of the aircraft.

asa wrote:One thing I noticed is that the diagram (which is awesome by the way) shows the Desser 850's being slightly bigger than Goodyear 850's. I think this may be backwards in reality.

However, your diagram also says "by stated diameter" so technically you're correct.

Can you elaborate? Are you saying the Goodyear 8.50x6 is actually larger in diameter? In width? vs the Desser?

asa wrote:An 8.50x10 seems like a decently popular choice that is left out.

I stacked the 8.50x10 and Desser, both stated at 22" in dia. Perhaps it would be good to add the width dimension to such a diagram since diameter is only one piece of the puzzle. Pizza cutter vs steamroller.

Zzz wrote:Can you elaborate? Are you saying the Goodyear 8.50x6 is actually larger in diameter? In width? vs the Desser?

I stacked the 8.50x10 and Desser, both stated at 22" in dia. Perhaps it would be good to add the width dimension to such a diagram since diameter is only one piece of the puzzle. Pizza cutter vs steamroller.

On the plane and aired up, the Desser and GY 850's are within like 0.5" in both height and width, but I thought the GY was the bigger one. Honestly, I'd probably just group the 850x6's together in the diagram.

Also I've never owned an 8.5x10, but there's no way it's the same diameter as an 8.50x6 is there?
http://bushwagoneast.com/8-50x6-vs-8-50x10/

Awesome job and super helpful!
Before reading this article, I hadn’t yet heard about the Desser 27” tires. A set of those on ABW 10” wheels looks like a relatively cost effective way to go.
I also echo the climb rate issue. When I had Gar Aero 29” tires on the 180, I noticed a significant climb rate loss but more importantly, I noticed a definite change in my climb out angle at VY. It was about five degrees shallower and most of the reason I took them off.
BCP Rocks!

asa wrote:
Also I've never owned an 8.5x10, but there's no way it's the same diameter as an 8.50x6 is there?
http://bushwagoneast.com/8-50x6-vs-8-50x10/

Unlikely, but it does appear to be close. Two different manufacturers + different target wheel diameter with the only constant being the tire width.

bushwagoneast....pfffft. You trust that guy?

Also I've never owned an 8.5x10, but there's no way it's the same diameter as an 8.50x6 is there?
http://bushwagoneast.com/8-50x6-vs-8-50x10/

Photo on that linked site shows about a 4" difference in diameter.
That's about right if the two tire's cross-sections are about the same,
but with a 4" larger diameter in the hole in the middle of one of them.

BTW good article Battson.

Zzz wrote:1. I suspect that tires, like many things, suffer from many cooks (mfrs) in the kitchen and naming standards are whatever they want. If 8.00 and 8.50 were specs for width, but their diameter happened to increase proportionally, that's just how it is. I imagine later on it became obvious that diameter was a better descriptor for what people value in a tire for light aircraft.

2. Is it confusing to have those two terms be interchangeable? A mounted tire's diameter is essentially also its height, unless you want to factor in compression under weight of the aircraft.

1) Yeah, that's my suspicion also. I was hoping someone could point to definitive history.

2) Yeah, I found it confusing. Choosing to use two different terms in the same article (and, indeed, even same block of text), looked to me like there was a deliberate attempt to differentiate between them. Could be just me, but I probably spent five minutes reading carefully to make sure I wasn't missing some explanation of deeper meaning.