Hey P180 owners, let’s talk tires for a moment. I’m getting outside edge tire wear, as has already been discussed. Mostly due to the gear geometry and how it contacts the ground.

But is there anything to mitigate it? Any gear “alignment” procedure to make the tires track a little straighter, or…? Modified strut pressure maybe?

Also, tire brand - the Michelin 028-357-x tires is what I’ve got. Anyone try the Goodyear 265K08-1 model that’s in the parts manual? Any different wear results? They seem to be a couple hundred$ more, but if they got 50% more landings or whatever it’d be worth the reduced frequency of changing.

While tires are not ridiculously expensive, the process of changing them is at best a hassle. So anything that can reduce that seems like a good idea.

Jon, can you rotate them (are they marked for one direction only?)? It's painful and might not be worth it.

I don't think you can change the touchdown geometry, as the suspension part is part of the leg. It's like an old VW swing axle in that sense. But maybe the camber can be changed to optimize, but then you ride on the insides during taxi - which wears the most?

Yes, I probably will since whether you rotate them or not the number of landings you get per tire change would be the same, you’d just get twice the landings per tire - no reason not to fully use the tire before replacement, I think.


Yeah, I don’t see any adjustment points but maybe someone knows something. I think decreasing the strut inflation might help it ride on the center of the tire a little better during taxi, and maybe even affect the geometry of toe in/out a little. But there is a minimum strut inflation called out with the increased gross weight SB. Not sure where I’m at relative to that limit, thought I’d see if anyone gets better results before I work too hard at some of these potential tweaks. Cheaper to learn from others’ experience.

The strut bottoms out in the runway first contact position, so pressure won't change any thing since that is the primary wear issue.

The MM may have tire alignment procedures and adjustments. Mine does for chamber and toe in.

Some wheels have NDT requirements on tire change (and a swap would be a change). You can't simply flip left/right mounted tires, you have to dismount and flip the tire around on the wheel.

Also, their can be parts which are designated for replacement on tire change. For me, there is a wheel half o-ring that costs $200 that is to be replaced on every tire change. Yuck.

Ideally, you get the CMM for the wheel so you know what it requires for tire change.


One approach is to have a spare set of wheels and that makes swap in/out easier, then you have time to flip tires later. Does require buying a spare set of wheels which can be major $$$. This also gives you spares in case you have wheel or tire trouble.

My tires are wearing very nicely. I thought for sure I would be needing a new set by now, but I've been very gentle on brakes, don't pivot in place, and my gear geometry is straight to the ground which protects the edges. I am very diligent about keeping them inflated to the upper end of the allowed range. Looks like I might get 500 landings on a set of mains, which is more than I was told to expect. They are Goodyears.

Mike C.

Mike, you made my day - finally, something on the Piaggio that is cheap.. paid $21.76 for the last o-ring when I recently replaced the left main..

David

Probably.

But during weight-on-wheels ops (taxi and takeoff/ldg) if the strut were less extended, the airplane would sit more on the center of the tire rather than the outside edges (changes with weight). I operated my MU2 with struts on the low end of the extension range for this reason and got very good, even tire wear from them. So perhaps strut adjustment could improve the issue.

Also, to my naked eye it looks like there is a bit of toe in while on the ground. I'm wondering if any wear might be exacerbated during W-O-W ops. It could just be visual illusion due to the length/shape of the airplane.

If I get motivated I will get a nice long straight edge - maybe laser would work, or a taut-ish string even - and will check the alignment of the wheels by measuring the distance of the straight line across the sides of each wheel/tire to some distance forward of the gear, and then measure the distance between those two lines. If they converge, there is a bit of toe in.


Yeah, only adjustment procedure I can find is for rigging the main drag brace over-center arm of the hydraulic actuator.

It's possible there's some kind of procedure for toe-in/out adjustment in the CMM for the gear, but that book is harder to come by.... (if anyone has one I'd be delighted to acquire a copy...)


Well, it may be worth exploring, but I would be surprised if wheels were not pretty big $.


I got very good life from Goodyear Flight Custom III on the Mits, and they seem to have deeper tread than the equivalent Michelins, which is why I'm wondering if anyone has them for the P180. Limited sample set, but I have never seen a P180 with tires other than the Michelins.

>Also, their can be parts which are designated for replacement on tire change.
>For me, there is a wheel half o-ring that costs $200 that is to be replaced on
>every tire change. Yuck.

There are places that can manufacture custom o-rings and seals to order.
Seem like if the owner specified and ordered them it would fall under the owner manufactured exemption.

$200 o-ring would piss me off.... (but I'm not flying a jet so YMMV)
Really large Viton ring might be that much, are the rings brown?

Annoys me, and I do fly a jet.


They are blue, fluorosilicone, due to the temperature range of -80 to 400 F.

I just need to measure them and it is likely they match some commercially available size you can buy.

For example, might be this one:

https://www.theoringstore.com/store/ind ... ts_id=6865

Just got to find the right cross section and diameter.

Mike C.

Who makes the wheel? I have the Cleveland/Parker CMM for the TBM and the big o-ring for the main wheels is M83461-1-261 right in the CMM. If you buy the Parker p/n 101-61200 it is $94, the Milspec one is $12

Who makes the wheel? I have the Cleveland/Parker CMM for the TBM and the big o-ring for the main wheels is M83461-1-261 right in the CMM. If you buy the Parker p/n 101-61200 it is $94, the Milspec one is $12

Goodrich 3-1490-1 (Textron PN 9912222-11).

I'd love to find a spare set of wheels to have spare wheel/tire assemblies (I have the tires, surprisingly), but the cost for that is major $$$. Current list for new is $43K/wheel ($28K from Textron). The only way this would work is if I find a used set somewhere.

Mike C.

I did manage to get a CMM for my wheels, both nose and mains.

The restriction on critical safety and maintenance information in the aerospace industry is criminal. It ultimately leads to less safety for all of us and more costs (in liability) for the manufacturers.

For example, PWC won't let me have access to the service bulletins on my engines unless I pay about $4K. Per year! WTF? Don't they want owners to know about SBs that come out and keep them informed? Apparently not.

None the less, some day, some where, I will gain access to them and download them all for my ever growing service library for my plane. I did mane to snag the engine MM and IPC, though, through various means.

I someday hope the right to repair movement includes aviation and manufacturers cannot withhold information from owners of their products.

Mike C.

Hey, good news, I just found that SkyGeek sells the wheel assembly for the Piaggio!

https://skygeek.com/goodrich-3-1461-1-piaggio-mwa.html

edit: And your Citation!

https://skygeek.com/goodrich-3-1490-1-cit-wheel.html

Boeing (former Avial) beats their price by $10K.

Both say a year lead time, however.

Let me guess, this wheel is not used on anything else.


I can buy two of mine for one of yours!

And get them in 6-9 days!

So there! :-)

Mike C.