uneven tire wear

[bobnoffs]

my main gear tires are wearing fast on the outboard edge. right tire is wearing faster. i imagine this is due to right seat is usually empty. i know shims are made for toe -in/ toe-out. could these be used to make the tire sit more ''upright''?
is it acceptable to move the mounted tires to rotate them or should they be dismounted? thanks for any advice.

 

[Cth6]

my main gear tires are wearing fast on the outboard edge. right tire is wearing faster. i imagine this is due to right seat is usually empty. i know shims are made for toe -in/ toe-out. could these be used to make the tire sit more ''upright''?
is it acceptable to move the mounted tires to rotate them or should they be dismounted? thanks for any advice.

Yes. Very common to flip a tire on the rim halfway through its life, not rotate left to right.

 

[ge9a]

I had this very problem about a year ago (after only a year or so of flying). I was really disappointed they only lasted a year (or just under a year!).

All I really did, after a lot of researching on this forum, is buy new tires and tubes, put them on, paying extra attention to bearing drag (not that it matters much regarding tire wear, but maybe), and now I really stay off the brakes as much as possible while taxiing or landing. They seem to be holding up a lot better than the original tires even though they are the exact same size and brand (from Van's).

As a side note, I also might add that for the first 10 or so flight hours, my brakes were really dragging, but fixed that and all is good now. I had the bolts at the bottom of the brake pedals, holding the calipers, way too tight, not allowing the brakes to fully release every time. Someone with WAY more RV time than any of use noted this, so I fixed it. It would probably have taken me way longer to figure that out had he not noticed it and pointed it out.

I put new main tires and tubes on at ~ 60 hrs of flight time (don't have the aircraft log here at the moment to check). As stated above, all seems good now without additional alignment work, or anything else really

Just food for thought.

 

[DHeal]

Outside edge tire wear is typical for the RV-12 due to the landing gear design and frequent flying with less than gross weight. Yes you can/should flip each tire on its wheel hub -- merely switching the wheel/tire assembly from one side to the other does not address the uneven tread wear issue. In my experience I have found that such flipping of the tires just about doubles the tire tread life -- wear off one side, flip the tire, and wear off the other side! For your edification, cut a cross-section piece across a used identical tire's tread to help visualize the amount of rubber remaining.

Be careful if you are using MATCO wheel hubs -- appropriate wheel rolling drag is a required aspect of the bearing tightening procedure. The MATCO procedure is to tighten up the axle nut quite a bit to ensure that the bearings are properly seated.

 

[gemiller]

Grove Airrcaft Landing Gear Systems sells shims. I installed a set and tire wear is now very even.

 

[avrojockey]

I wouldn't mess with shims. That will never fully fix the wear attributed to touchdowns happening on the outboard edge, due to the natural sag of mains when weight-off-wheels. I would just flip the tires.

FWIW...wear rates can very extensively due to rubber composition. With new Goodyear Flight Special II, I was having to flip them every 75-80 landings, but Wilkerson retreads are really good. They last about 200 landings before I need to flip them

 

[Piper J3]

New tires are made with a single rubber compound that is optimized for sidewall flexibility and not necessarily for thread wear. When retreading a carcass, a much harder rubber can be applied for the tread while sidewall remains per original design. This makes for an unusually robust tire.

I installed Desser 500-5 6 PLY RETREAD "ELITE PREMIUM 2-GROOVE" tires at 525TT and now have 930TT. I have not flipped tires on the rims but may do so next annual inspection. The Desser 2-groove tires have a squared-off thread that has a heavy section of rubber at the edges of the tread making for ideal wear when aircraft touches down with tires canted at high camber angle to the ground.

Note: These tires are slightly larger diameter, wider, and heavier than Van’s supplied Aero Classic tires. The opening in the wheel fairing must be enlarger to allow ½” clearance.

Photos below show install at 525TT and again at 845TT…

 

[seagull]

Jim,
Are you still flying off your own grass strip? The Desser retreads do last long plus give a little more ground clearance for the pants. I get about 500 hours, but that is on pavement.

 

[gemiller]

I wouldn't mess with shims. That will never fully fix the wear attributed to touchdowns happening on the outboard edge, due to the natural sag of mains when weight-off-wheels. I would just flip the tires.

FWIW...wear rates can very extensively due to rubber composition. With new Goodyear Flight Special II, I was having to flip them every 75-80 landings, but Wilkerson retreads are really good. They last about 200 landings before I need to flip them

My experience thus far is that the shims have significantly reduced the uneven wear on my RV-12. The natural sag that you mention is reduced with the addition of the shims.

 

[Piper J3]

Jim,
Are you still flying off your own grass strip? The Desser retreads do last long plus give a little more ground clearance for the pants. I get about 500 hours, but that is on pavement.

Correct... I fly off of a grass strip. Almost all my flights entail 1-2 landings on hard pavement.

As long as we’re talking about tires and landing gear… it would be a good time to mention SB-00040. It is very easy to visually inspect the aluminum landing gear carry-thru gear channel for cracks that emanate where the u-clamps mount. The bird-mouth openings in the channel are a point of stress concentration. I know of two RV-12’s (mine included) that had cracks in this location. See photo below.