Tires/Gear Leg/Toe In

[Bryan Cotton]

Wow. Are you sure you have the correct alignment? I guess you can extend that if you swap them every oil change. Any opinions if it would be ok to just swap the whole wheel, in which case the direction of rotation would be reversed? Is there a bearing problem if you do this?
Gordon

Gordon,
I followed the alignment procedure in the plans but I suspect it is off. I will be measuring and correcting it at the next condition inspection. That profile is not wear, but the quality of the Cheng Shin tire showing through. Had that shape when new, but looks normal when inflated.
Swapping the wheel is not a good option, because the tires wear on the outside due to camber. The inside must become the outside to get maximum life. I also swap left and right as my right tire wears more quickly.

[tps8903]

Started swapping my tires tonight. This is about 110 hours or so.

new vs old tire.png

Is the wear on the outside or inside of the tire? Mine was the inside of the tire. The extreme toe out was dragging my gear down trying to spread the tires. I would assume you have a bit of an opposite issue with too much toe in.

I only got about 30 pavement landing on my Cheng Sing tires before one blew out. The other 40-50 landings were on turf.

I'm going to rotate the axles, see how much it takes. If I can up drill with a custom jig to cover the size of the new hole, then I'll do that. Otherwise I'll elongate the original weldment hole, use that to clamp the weldment in place (like a set screw) and use my drill jig to drill a second hole about 3/4" above. This should prevent the weldment from walking around when I redrill it.

Because the original bolt will act as a set screw, I might do the final alignment in taxi position with weight in wheels with grease plates, then I know for sure what it is once the plane is in taxi position. My assumption for why this is done in the air is because normally the weight on the axles would cause them to shift while drilling.

[Bryan Cotton]

Is the wear on the outside or inside of the tire? Mine was the inside of the tire. The extreme toe out was dragging my gear down trying to spread the tires. I would assume you have a bit of an opposite issue with too much toe in.

Definitely on the outside. Regardless of toe there is a lot of camber. I would not have guessed anybody would have wear on the inside!

[Skippydiesel]

I think it would be helpful if you gave your tyre pressures - On my new Sonex Legacy (45 hrs) I am using 35 psi, operating almost exclusively of grass and so far no sign of unusual wear (actually tyres still look new)

[Bryan Cotton]

I think it would be helpful if you gave your tyre pressures - On my new Sonex Legacy (45 hrs) I am using 35 psi, operating almost exclusively of grass and so far no sign of unusual wear (actually tres still look new)

45-55 psi.

[Skippydiesel]

I think it would be helpful if you gave your tyre pressures - On my new Sonex Legacy (45 hrs) I am using 35 psi, operating almost exclusively of grass and so far no sign of unusual wear (actually tres still look new)

45-55 psi.

Thanks Bryan - that's quit a wide pressure range for such a small tyre. My tyres are Goodyear Flight Custom III, 5.00-5, if failing memory is good Max 50 psi.
Would the tyre make/model change your recommendation?

[Bryan Cotton]

Thanks Bryan - that's quit a wide pressure range for such a small tyre. My tyres are Goodyear Flight Custom III, 5.00-5, if failing memory is good Max 50 psi.
Would the tyre make/model change your recommendation?

Skippydiesel,
From memory the Sonex recommendation is 50-55 psi. My Cheng Shin tyres say max 70 psi on them. The rims are cast at max PSI 30. My understanding with the stock sonex wheels and tyres is that running low pressure, like 30psi, can lead to the tyre/tube spinning on the rim. This causes a failure at the valve stem. I've heard a Sonex employee say he would like to grind off the 30PSI off the wheel casting, as low pressures have caused a lot of grief.

Typically when I fill mine I go right to 55 psi. They never stay there, but they don't seem to go below 45 psi. So I fill them to 55 and leave them alone as long as they are at least 45. That is where I get my range from.

185 hours and hundreds of landings and those pressures have served me well. Now I just need to get the alignment figured out.

[daleandee]

Typically when I fill mine I go right to 55 psi. They never stay there, but they don't seem to go below 45 psi. So I fill them to 55 and leave them alone as long as they are at least 45.

My older rims didn't have the 30 psi limit but the ones I have now do. I've always used 50 psi as my setting but even with the famous "Leakguard" tubes I still check & set the pressure about once a month. I too understand that a lower pressure can lead to tire spinning & tube failure.

One of our Sonex flyers here has said that 50 psi using the factory 11x4-5 tires is correct but that larger tires (5" or larger) would mandate using 30 psi for a limit as 50 psi with the larger tire puts too much stress on the rim.

I've always used the factory recommend tires on both of the Sonex aircraft I have owned (16 years total) with 50 psi as a limit and have never had a flat.

I replaced my last set of tailwheel tires at ~200 hours with many landings and my worst tire looked excellent compared to what you posted (I still had tread all the way across). 8~)

[Skippydiesel]

The Goodyear chart would suggest Goodyear Flight Custom III, 5.00-5, Rated Pressure, range from 31 psi for the 4 ply up to 50 psi for the 6 ply (I will check what ply rating I have)

https://www.aps-aviation.com/wp-content ... e-data.pdf

[N190YX]

Regarding the Goodyear Flight Custom III tires, while they will wear longer than just about any other tire except the Desser Monster retread*, they weigh 2 or more pounds more per tire, depending on the size. It is ~2 pounds more in the 500-5 tire size. That is four extra pounds on a tail dragger Sonex if you are using 500-5 tires! *Retread tires are commenly used in aviation with good results, the airlines and the Air Force use retreads almost exclusively.