Tires

[GraemeSmith]

After 42.1 hours and about 128 landings, I rotated my cheng shin tyres as the outside edges were pretty worn. I used the Sonex tooling to set alignment during the build and was pretty meticulous about it. It seems like the gear is set for toe-in which makes it pretty forgiving, but it seems hard on the tires. Also I wonder if this is making the shimmy worse.

Sounds about right. Those 4" tires are small, soft and not very hard wearing. That's about what I got on well aligned wheels.

I put on tundra tires (Airhawk 5 x 5.00). I got 400+ landings before I handed them and expect to get about another 400 landings out of them and still have a small amount of even tread wear left after I do and come to replace them.

[peter anson]

For those of you guys who are getting a lot more out of your tires, are you:
1) just better pilots (likely even if this is not the root cause)
2) flying off of grass
3) flying on gear aligned differently than mine

Wheel alignment has a big effect. Some years ago I had recently replaced the tyres when I did a very poor landing at an unfamiliar airfield in challenging conditions. My new tyres subsequently wore noticeably in a very short time, only 24 landings of which only 14 were after the hard landing. I found that I had bent the gear legs slightly and straightening them fixed the high wear problem.

Peter

[pfhoeycfi]

I set up my alignment per Sonex and then checked and rechecked. Then I broke it down and set it up again, check and recheck...then a third time...then I drilled. And I have a shimmy. I recall w the Sonerai that it was easily shimmed...not an option w the Sonex. Once you drill, it is what it is. I'm interested too on how others have approached this . During the build the two things that worried me most were the fuel tank...which did collapse (I replaced), and the landing gear....

Peter

[GordonTurner]

Hi Peter.

…..not the canopy? I’m just waiting for warmer weather in the spring to build my canopy, and dreading it during every cold minute in between!!!

Gordon

[builderflyer]

Looking at my notes from over 16 years ago it appeared to me that this toe-in thing is much more complicated than one might first think. The plans call for 0.7 degrees toe-in and that is with the aircraft leveled and no weight on the wheels. But if you measure the gear alignment with the taildragger in a 3 point stance with weight on the wheels, you'll find that there is a toe-out condition. So tire wear may be somewhat dependent on what type of take offs or landings are typically made in the aircraft. The higher the tail is on take off or landing relates to a more toe-in situation and the lower the tail is on take off or landing relates to a more toe-out situation. But wearing the tires on the outside edges may have as much to do with the camber the wheels experience when the gear is lightly loaded than anything else. I assume that because my tires also wear on the outside edges despite that all my take offs and landings are made 3 point.

Regarding correcting the toe-in angle on the left wheel from what was initially set, I was able to upsize the 1/4 inch hole to 5/16 inch without the need to drill any new holes, sort of like what Randy said he did except using a 5/16 inch bolt instead of the original 1/4 inch bolt.

All the above is just my opinion and that's been known to be wrong before.

Art,,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,Jabiru 3300 #261

[Bryan Cotton]

I think my next step in the journey is to ballast the aircraft, and measure what I have in 3 point and level attitudes. I'm going to wait until Adam is back in school.

[builderflyer]

I think my next step in the journey is to ballast the aircraft, and measure what I have in 3 point and level attitudes. I'm going to wait until Adam is back in school.

As you probably realize, Bryan, to get reliable readings of toe-in or toe-out with weight on the wheels, it's really necessary to have zero friction between the tires and the surface they sit upon. I've heard that some have used greased steel plates to accomplish this but I didn't go to that trouble. But I did notice how the angles changed depending whether I had rolled the plane forwards or backwards just before taking a reading. Will be interested to see what you come up with.

Art,,,,,,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,,,,,Jabiru 3300 #261

[Bryan Cotton]

I planned a piece of wood under one tyre. Under the other, a steel plate with rods underneath to let it roll outward.

[goldthwaite flyer]

I'm also needing to replace tires. Currently have the cheng shin 8 ply and sticking with those. Is it recommended to change tubes when you change tires?

[nwawingman]

I definitely would replace tubes at same time replacing tire.