rotate the tires?

[Bill_Pyles]

Mooney main landing gear is rigged such that the wheel/tire assembly has positive camber which causes the outside of the tire tread to wear faster than the inside.  

Is there any reason the tires cannot be rotated on the rims so as to extend the life of the tires?  I realize some tires have a rotation direction and shouldn't be reversed, but if the tires can rotate either direction does anyone rotate their tires?

 

[Marauder]

4 minutes ago, Bill_Pyles said:

Mooney main landing gear is rigged such that the wheel/tire assembly has positive camber which causes the outside of the tire tread to wear faster than the inside.  

Is there any reason the tires cannot be rotated on the rims so as to extend the life of the tires?  I realize some tires have a rotation direction and shouldn't be reversed, but if the tires can rotate either direction does anyone rotate their tires?

 

I have never rotated them and interestingly can't say I saw the outer edges wear quicker than the inside. I guess I should go under the plane and do some measuring with my micrometer. 

[carusoam]

1) In a perfect world... the edges will wear...  see which edge it is... it will be based on the LG’s set-up... inner edge? It’s not from cornering like a car would wear....

2) in a not so perfect world a flat spot or two will be more of a challenge...

3) In the automotive world, people avoid reversing the rotation direction of tires... heavy breaking is stronger than heavy acceleration... but are opposite forces... on the same tire... Aviation has neither heavy braking or acceleration provided by the tires...

4) Some automotive tires have asymmetric thread patterns that are best to keep the water moving away.... avoiding hydroplaning... aviation has a completely reversible tread pattern...

5) The cost of swapping out tires for this purpose seems to be expensive... the cost of the tire nearly equals the labor to change it out...

 

Try as I might.... I’m not coming up with a technical reason that they can’t be rotated as needed...

PP thoughts,

-a-

[takair]

35 minutes ago, Bill_Pyles said:

Mooney main landing gear is rigged such that the wheel/tire assembly has positive camber which causes the outside of the tire tread to wear faster than the inside.  

Is there any reason the tires cannot be rotated on the rims so as to extend the life of the tires?  I realize some tires have a rotation direction and shouldn't be reversed, but if the tires can rotate either direction does anyone rotate their tires?

 

Interesting, mine wear faster on the inside, though I can't quite figure out why.  It seems more intuitive that the outside would wear first.  I have thought about doing moving them to get more life, but find I am too lazy to do it.  I suspect it is worth a few extra landings, so I would be changing the tires again in a few hours.

[carusoam]

Rob,

Take a picture of our MLG... you will see a slight angle to the gear legs and tires?

Probably caused by the over centering locking mechanism...

Redesigning the MLG to go ‘over center’ and stay perfectly vertical would be an interesting improvement...

Somebody at the factory would be interested in that....

Best regards,

-a-

[jaylw314]

3 hours ago, Bill_Pyles said:

Mooney main landing gear is rigged such that the wheel/tire assembly has positive camber which causes the outside of the tire tread to wear faster than the inside.  

Is there any reason the tires cannot be rotated on the rims so as to extend the life of the tires?  I realize some tires have a rotation direction and shouldn't be reversed, but if the tires can rotate either direction does anyone rotate their tires?

 

Positive camber is useful because under load, camber tends to decrease.  So as you put more weight on the plane, he camber should get closer to zero.  I assume that the amount of positive camber is designed so that most of it zeros out under typical dynamic loads on landing.

There are some concerns about deflating and reinstalling tires in terms of pinching inner tubes and increasing the risk of punctures.

Automotive tires are only direction limited by tread pattern, which channels water out better in one direction.  Otherwise, even asymmetric tires can be rotated, as long as the outside remains facing outside.

[steingar]

Tires are cheap, comparatively.  I'll change them when they wear out.  I'd just as soon do as little maintenance as I can on the aircraft, since every time the aircraft is maintained it can be maintained incorrectly.  

[EricJ]

55 minutes ago, jaylw314 said:

Automotive tires are only direction limited by tread pattern, which channels water out better in one direction.  Otherwise, even asymmetric tires can be rotated, as long as the outside remains facing outside.

Most asymmetric automotive tires can be flipped on the rims and run backwards, even if the sides are marked "inside" and "outside".   We do this with track tires all the time, as usually the outside edge wears faster than the inside, so you can get a bit more life out of them if you flip them after a while.    At our last event I ran the second day with two flipped tires on one side and two non-flipped tires on the other and it was still fine.

[jaylw314]

1 hour ago, EricJ said:

Most asymmetric automotive tires can be flipped on the rims and run backwards, even if the sides are marked "inside" and "outside".   We do this with track tires all the time, as usually the outside edge wears faster than the inside, so you can get a bit more life out of them if you flip them after a while.    At our last event I ran the second day with two flipped tires on one side and two non-flipped tires on the other and it was still fine.

In theory, most performance tires have a tread design or different compound on the outside that can better withstand the wear compared to the inside, so flipping it around would mess up that carefully engineered design.

In practice, I think this is a load of marketing BS that the tire makers sell us on, and I'd agree it probably makes no difference.

[EricJ]

1 minute ago, jaylw314 said:

In theory, most performance tires have a tread design or different compound on the outside that can better withstand the wear compared to the inside, so flipping it around would mess up that carefully engineered design.

In practice, I think this is a load of marketing BS that the tire makers sell us on, and I'd agree it probably makes no difference.

I think they used to do that with motorcycle race tires, i.e., the edge compound was softer for more cornering grip, while the center of the tire was a little harder compound.   I don't know whether that was successful enough that they still do it or not.

General Aviation airplane tires are about as basic as they come, though, so I don't think flipping them hurts anything.   I seem to remember doing this frequently on the Cessnas when I was a lineboy in the Dark Ages.

[Bill_Pyles]

Thanks to all of you.  Based on the information you've shared (and my own experience with car tires and racing tires) I will ask a mechanic to rotate the tires on the rims, hoping he/she won't object due to liability or fear.

Attached are photos of my plane and tires in question.  Obviously, I've flat-spotted the right one.

--Bill

[Gary0747]

They say you should not reuse tubes for fear of pinching or getting a wrinkle that eventually causes a hole. The price of a good tube can be 60 to 75 pct of a new tire unless you are running something like a Goodyear flight custom.  

[N201MKTurbo]

Every annual the tires should come off to inspect the wheels. Even if they don't take the tires off you can swap the wheels left to right while it is up on jacks with very little effort.

The point is don't make a special maintenance event out of it just have your guy do it at annual. it will cost almost nothing.

[jaylw314]

24 minutes ago, N201MKTurbo said:

Every annual the tires should come off to inspect the wheels. Even if they don't take the tires off you can swap the wheels left to right while it is up on jacks with very little effort.

The point is don't make a special maintenance event out of it just have your guy do it at annual. it will cost almost nothing.

That sounds like a good policy

 

[carusoam]

Bill’s last pic is showing a light flat spot...  low tread in one spot...

At least we know what one looks like...   (I’ve seen a few)

amazing how much rubber gets rubbed off like that ...

Best regards,

-a-

[Guest]

Mooney landing gear have fixed length side braces, many sit at weird angles, less that 90 degrees to the surface.  Pipers have adjustable side braces.

Clarence

[RLCarter]

Directional rotation tires also has to do with the layering, dual compounds are still used on Motorcycles, it was common practice on the trainers to switch the wheel assembly from one side to the other during the 100 hr inspection to get the most wear out of tires

[bradp]

I used to ask that my tires be rotated on the rims every annual and I haven’t for he last three. Now I’m noticing some uneven wear and will have them rotated this annual. 

[Guest]

3 hours ago, RLCarter said:

Directional rotation tires also has to do with the layering, dual compounds are still used on Motorcycles, it was common practice on the trainers to switch the wheel assembly from one side to the other during the 100 hr inspection to get the most wear out of tires

In a Mooney, with both mains at an angle as is common, switching the entire wheel from side to side will do nothing other than spend your money.

Flipping or rotating them will even out the wear.

Clarence

 

[Mooney in Oz]

4 hours ago, M20Doc said:

In a Mooney, with both mains at an angle as is common, switching the entire wheel from side to side will do nothing other than spend your money.

Flipping or rotating them will even out the wear.

Clarence

 

An old aircraft mechanic who used to look after my Mooney many years ago told me the wearing out on the outside tyre was due to the culmination of many xw landings on that particular side.

Clarence?

[DonMuncy]

17 hours ago, N201MKTurbo said:

Every annual the tires should come off to inspect the wheels. Even if they don't take the tires off you can swap the wheels left to right while it is up on jacks with very little effort.

 

Am I missing something? If you take a wheel off the left, and move it to the right, won't that put the outside from one side to the outside of the other? Assuming the camber is the same on each side, it looks like the wear would not be affected. 

[MARZ]

 

9 minutes ago, DonMuncy said:

Am I missing something? If you take a wheel off the left, and move it to the right, won't that put the outside from one side to the outside of the other? Assuming the camber is the same on each side, it looks like the wear would not be affected. 

Exactly - that and your moving the rotor to a different set of pads - not a really good idea.

I've got an awful lot of landings on a set of Air Hawk tires stuffed with Michelin airstop tubes - my thinking is that I'm not going to risk an expensive tube to extend the life of an inexpensive tire by flipping the tire each year.   The CBC has to have some limits LOL

[bradp]

When your wheels are disassembled at annual simply rotate each tire (tyre for Andrew et al) 180 degrees about its axis on the same wheel. 

[N201MKTurbo]

1 hour ago, DonMuncy said:

Am I missing something? If you take a wheel off the left, and move it to the right, won't that put the outside from one side to the outside of the other? Assuming the camber is the same on each side, it looks like the wear would not be affected. 

No, you not missing anything, you would have to take the tires off the rims. It occurred to me too just after I posted it, but I haven't had time to correct it.

[jetdriven]

The tubes cost almost 100$ each, substantially more than the Desser retreads that have gone 4 years now. Reusing the tube is risky for a  fold which chafes through or a pinched tube, both of which leave you stranded. So ideally it would be nice, but practically and financially speaking, just run the tires. If one wears more unevenly than the other, swap the mains left to right to even it out.