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Uneven Tire Wear, Excessive Camber

RonS

Member
I just replaced my left main tire after only my first 120 landings. The outside of the tire was extremely worn. See photos. I did a quick check with a digital level against the left wheel and found approximately 5 degrees of positive camber. In contrast, the right side is only about 1 degree positive. The right tire seems to be wearing more or less evenly. In the attached photo of the airplane you can actually see the difference in camber by eye. I emailed Van's to see what they recommend. Anyone else run in to this?

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Those look like the aero classic tires, correct? You'll get better treadwear out of some of the other brands of tires, and although you're correct that your wear is a far heavier on that one tire possibly due to camber, you're probably always going to have to get used to flipping the tires on the rim part way through the life cycle so that you can wear the other side. It's just the way the gear hangs when unloaded in flight. I run Desser retreads, which tend to have thicker and longer lasting rubber. If you get some of the "monster" varieties, you have to make sure you open up the hole in the fairing a little so you don't damage the fairing, but Desser makes a variety of retreads.

What I'm not sure of is if you have any options to get rid of some of the camber.
Perhaps some shims similar to the ones used to adjust toe?
 
I would not say this is a normal wear. Mine did wear on the outsides which is normal for a RV but pretty much evenly and also not so excessively.
 
taxi turns, wind

Food for thought...do you have lot of turns when taxiing back to your hangar that would wear one side more than the other? Wind that blows from one direction all the time while taxiing? Cross wind touch and goes where the wind is always from the same side?

There's probably a good reason for the uneven wear, but none-the-less, rotate the tires and carry on.

Those tires are known to wear out pretty fast too, and rotation each year is to be expected. More often if you enjoy touch and goes like I do.
 
Purchase a 4 degree wedge to put between the axel and the gear leg. AC Spruce sells them; do not know if Vans does or not.

Over the years I have used them on a few Cessna's; some for toe in corrections, some for camber. Not sure which you need might contact Grove directly;here is Spruces picture https://www.aircraftspruce.com/search/search.php?s=axle shim 6102-3

Thanks. That's what I was thinking would be the best solution... Just wanted to check to see what Van's says. I don' know if there are an limitations on the amount of camber that can be shimmed out.
 
Thanks. That's what I was thinking would be the best solution... Just wanted to check to see what Van's says. I don' know if there are an limitations on the amount of camber that can be shimmed out.

I am not sure if you built the plane or purchased, during the build VANS has a method of measuring and they have different size shims that will go between the axle and landing gear based on what you find during that measurement.
 
Those look like the aero classic tires, correct? You'll get better treadwear out of some of the other brands of tires, and although you're correct that your wear is a far heavier on that one tire possibly due to camber, you're probably always going to have to get used to flipping the tires on the rim part way through the life cycle so that you can wear the other side. It's just the way the gear hangs when unloaded in flight. I run Desser retreads, which tend to have thicker and longer lasting rubber. If you get some of the "monster" varieties, you have to make sure you open up the hole in the fairing a little so you don't damage the fairing, but Desser makes a variety of retreads.

What I'm not sure of is if you have any options to get rid of some of the camber.
Perhaps some shims similar to the ones used to adjust toe?

Yeah... these classic aero tires are pretty soft. I am planning to upgrade to a better tire but wanted to correct the issue before I just made it a more expensive problem. So i just bought another cheap one for the time being. The tires only have about 60 hours and 100 or so landings on them. The thought of rotating tires every 30 hours is a less than appealing prospect. That's be every other month. Hoping I can use shims or some other method to correct the excessive camber on that wheel then get better tires for a more durable solution. I'll keep everyone posted as I hear back from vans and decide what to do.
 
Do not forget about P-factor and torque on the takeoff roll. They put more load on the left tire and having RIGHT rudder input does not help. Pretty typical of all light aircraft that has lots of power to weight.
 
There is also this positive camber on my 14, but the tires are very little and symmetrically worn after more than 250 landings (Michelin Pilot).

Could this rapid wear not also come from a lack of parallelism ?
 
Had one customer come in with persistent tire wear similar to yours but not as dramatic. Did all kinds of trouble shooting to figure out the cause, nothing. One day I was riding with him & noticed he tended to yaw the plane in flare, every time. He didn’t realize he was doing it, essentially scrubbing the tread off his left tire every time he landed.

I don’t think this is the problem here though. I notice the sawtooth pattern around the tread outter edge. From my days in a tire shop long ago, we’d say you probably have a Toe-in problem compounded by the camber issue.
 
I am presently building a 14A and happen to be working on Section 40A which states that shims are available for order on the Van's website if you too much toe in or out camber. This is determined using a string and is documented in the instructions.
 
Just FYI, your problem is not caused by the camber. It’s caused by too much toe in. Get a laser tool, level the airframe and measure the actual amount of toe in/out of each wheel. Then order the appropriate spacer for each axle to get you as close to zero toe as possible. If it’s close, very slight toe out is preferred over toe in.

These are just my opinions based on 30 years of building 6 airplanes and a lot of experimentation on gear configuration, especially on my Rockets.
 
Just FYI, your problem is not caused by the camber. It’s caused by too much toe in. Get a laser tool, level the airframe and measure the actual amount of toe in/out of each wheel. Then order the appropriate spacer for each axle to get you as close to zero toe as possible. If it’s close, very slight toe out is preferred over toe in.

These are just my opinions based on 30 years of building 6 airplanes and a lot of experimentation on gear configuration, especially on my Rockets.

I will check the toe-in. Do you know if this can be done with the airplane resting on the gear or do I need to jack it up?
 
I too have camber but did add shims to address a toe out on one side. No sign of tire wear at 80 hours. Look at 40B-06.
 
I will check the toe-in. Do you know if this can be done with the airplane resting on the gear or do I need to jack it up?

No you don’t need to Jack up the airplane but I would measure the toe with the airplane in the landing configuration, weighted to your typical operational weight, with the mains on grease plates.

It’s a lot of work but pays off in better tire wear and improved handling at high speed. I actually changed shims on my Rocket three times before I was happy with it.
 
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Just FYI, your problem is not caused by the camber. It’s caused by too much toe in. Get a laser tool, level the airframe and measure the actual amount of toe in/out of each wheel. Then order the appropriate spacer for each axle to get you as close to zero toe as possible. If it’s close, very slight toe out is preferred over toe in.

These are just my opinions based on 30 years of building 6 airplanes and a lot of experimentation on gear configuration, especially on my Rockets.

Since shims in very small angle increments are available, suggesting any toe out is bad advice in my opinion.
If a builder has to accept any amount of mis-alignment, slight toe in is preferable to toe out because all of the different landing gear loads (braking, rolling drag, tire spin up, etc), will generally add a toe out change.

Builders should also note that adjusting for neutral alignment is only valid with the wheels on the ground (and on grease plates) and the airplane loaded to an average percentage of gross weight.
If you follow the build manual and adjust the gear alignment while assembling the landing gear, the specified toe in value should be used.
 
When I wrote my response I KNEW that Vans recommended slight toe in. I could not disagree more. We could rehash all the engineering logic but there’s no point to it. To each their own. Do what works for you.
 
Grease plate alternate

And if you don’t know the poor racers (As in most SM racers) grease plate trick...a clean heavy duty garbage bag folded over a couple time on a smooth surface is very camber / toe / suspension settling friendly. The will allow the tire to slide all around while taking weight.
 
When I wrote my response I KNEW that Vans recommended slight toe in. I could not disagree more. We could rehash all the engineering logic but there’s no point to it. To each their own. Do what works for you.

True.... Engineers love to argue a particular design philosophy ;), but on this particular topic there is a lot of aircraft design publications that support the toe in position as a standard.
Particularly with legs that sweep aft and will change toe alignment as the leg deflects under load.
 
Uneven tire wear

Curious if Vans replied. I have the exact same issue on my 6A, except my unevenly worn tire is my right side, and its worse than yours! I almost threw up when I took the fairing off for a close look. Did you shim it?
 
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