I've heard comments on this site (mostly from one person) that airtrac 850's
1) are smaller than GY 850's,
and
2) don't wear as well as GY's.
My C180 had a set of Desser-recapped 850 GY's on it when I bought it (they wore like iron BTW).
I replaced them with a set of Airtrac 850's,
and didn't notice any significant difference in size.
3-1/2 years later, I have 874 landings on those tires, mostly on paved runways,
and they still have a lot of life left in them.
So they seem pretty durable to me.
FWIW that same person always sez the 26" GY's are hardly any bigger than 850's,
here's a pic of a 26" GY next to a mounted 850 GY recap.
View attachment 65841
And a pic of a 26" GY compared to an 850 airtrac.
View attachment 65842
Well, that "someone" would be me, I'd guess.
1) I stand by my statement that Goodyear (and Michelin, BTW) are larger in diameter than the Airtrac 8.50s. Perhaps the Airtracs have increased in size, but those "smooth 8.50s" they put out look tiny by comparison. I've actually put MOUNTED Airtracs next to MOUNTED Goodyears, and there was a good inch difference in diameter. BTW, those came off the same airplane, a 185, that had some handling issues..... Is the difference in size huge? No. But, as Steve Pierce alluded to in this thread, the Airtracs have a much more rounded profile, where the Goodyears have a much more square profile. Put a load on those different tires at operating pressures and measure them.....that's where it actually counts, NOT uninflated, laying on the floor.
2) I've run quite a few tires over the years on various airplanes. It has now been quite a few years since I ran Desser 8.50s because, as others have noted, I just got a LOT more wear out of Goodyear tires. That's my experience, your experience may differ. So be it.
As to your photos, I think you need to consider comparing apples to apples.....for example: "here's a pic of a 26" GY next to a mounted 850 GY recap." A SMOOTH GY recap may or may not represent an actual Goodyear production 8.50. And, the 26 inch Goodyear is not inflated, which generally tends to splay the tire out some. Comparing a mounted and inflated tire to an uninflated tire can be misleading.
Then you compare a 26 inch Goodyear to a Desser 8.50. As I noted, the Desser 8.50s have a rounded profile, and aren't that large in diameter anyway.
When discussing the Goodyear 26 inch Blimp tires, the argument that many suggest is that they are actually 26 inch diameter tires. They are NOT 26 inch diameter tires when inflated to operating pressure and mounted on an airplane. Compare a Goodyear Blimp tire to an actual 26 inch tire, such as an Alaskan Bushwheel 26 inch, and you'll see how much smaller they actually are. They're much closer in diameter to an inflated Goodyear 8.50 than they are to an actual 26 inch tire. The blimp tires are WIDER than an 8.50 tire, and that's important when it comes to floatation. Pick your medicine. The single biggest issue with the Blimp tires is that there are very few approvals for them on production aircraft.....and they are heavy.
Finally, I have had two faulty Desser tubes recently, and will never purchase their tubes again. I know two others who've had similar experience. I hope Desser figures that out and fixes it, but till then, no thanks.
In the spirit of full disclosure, I am now running Desser Air Trac 8.50 x 10 tires on my airplane, mostly because the Goodyear 8.50 x 10 tires have more plys and are HEAVY. I'm actually hoping these tires will wear a bit, frankly. Time will tell, but so far, so good. Goodyear natural rubber tubes, BTW.
A fellow I know installed a set of the Desser smooth 8.50 x 10 tires last year, and they are cracking badly already. Bad batch? I dunno, my treaded 8.50 x 10s seem to be holding up after a year and a half.
I have just NEVER had a bad Goodyear aircraft tire or tube, and I had a set on my 170B for a loooong time, always parked outdoors. I have had bad Desser tires and bad Desser tubes.
That's my experience. As to sizes, it's all relative, so pick the flavor that winds your watch. But compare apples to apples.
MTV