Help Please - Excessive Tire Wear

ZU-RVZ · #1 04-02-2007, 01:12 AM

Hi,

My 7A has 40 hours TT and 46 landings.

I noted this weekend that the left tire has worn almost to the canvas on the outside. I know that RVs always wear outside first due to the leg geometry, but 46 landings is ridiculous!

I did not build the plane myself but suspect alignment that would cause scuffing and premature wear. I have not checked alignment.

Is this possible and more importantly, how can I fix it?

I fixed an alignment problem a few years ago in a 206 with shims, but the RV design does not accommodate this.

I look forward to your advice.

Chris Spencer-Scarr

Kyle Boatright · #2 04-02-2007, 04:59 AM

I experienced the exact same thing on my first set of tires. Then I learned to hold some right aileron during the takeoff run and now the tires wear pretty evenly.

f1rocket · #3 04-02-2007, 08:42 AM

It only takes a few minutes to check the alignment. Sounds like that's your problem from the way you've described it. Van's sells axle shims (others as well) that will correct minor variances.

Remember that after you correct it (with shims or otherwise) your wheelpants and LGIF most likely won't fit as well anymore. On my Rocket, I went for zero toe-in and zero incidence with a full fuel load. I didn't get it exact but pretty close. I have over 140 hours on the original rubber and it shows very little wear.

DGlaeser · #4 04-02-2007, 01:42 PM

Quote:

Originally Posted by f1rocket

It only takes a few minutes to check the alignment. Sounds like that's your problem from the way you've described it. Van's sells axle shims (others as well) that will correct minor variances.

Remember that after you correct it (with shims or otherwise) your wheelpants and LGIF most likely won't fit as well anymore. On my Rocket, I went for zero toe-in and zero incidence with a full fuel load. I didn't get it exact but pretty close. I have over 140 hours on the original rubber and it shows very little wear.

Are those shims applicable to a 7A? The Vans website shows them being for the 'separate RV8 axle'. I didn't think there was any way to adjust the gear alignment on the A models (unless you want to drill a different bolt hole through the gear & weldment).

Build9A · #5 04-03-2007, 08:39 PM

Could the left brake be sticking? Vans brake cylinders have a tendency to stay just a little compressed. I had to add springs on each cylinder to keep them in the off position when not depressed. I'm not sure if it would cause the amount of wear that you describe. take care.

brianwallis · #6 04-06-2007, 09:12 AM

Put some Wax paper on the floor and move the main wheels over the wax paper.. if the paper turns left or right.. Wah LA! that will tell you what it's doing.
Best
Brian

gmcjetpilot · #7 04-06-2007, 05:15 PM

Quote:

Originally Posted by brianwallis

Put some Wax paper on the floor and move the main wheels over the wax paper.. if the paper turns left or right.. Wah LA! that will tell you what it's doing. Best Brian

Cool trick and great advice above by everone. Not to repeat the likely reasons already mentioned, minor reasons are quality of original tires (some brands last way longer), landing surface (big airports with harsh rain grooves). Other reasons: Air pressure? Landing fast? Using brakes hard to get short roll out?

It does sound wear is too uneven and life too short by at least 1/2. Consider also rotating tires. Unfortunately you have to remove them from the rims and rotate tire on rims, which is a pain. I got a few 100 hours out of my tires.

Adjustment? Call Vans gear maker. If its significant, several degrees, I don't know for sure, but he might be able to tweek or bend gear.

rvbuilder2002 · #8 04-06-2007, 11:06 PM

Quote:

Originally Posted by brianwallis

Put some Wax paper on the floor and move the main wheels over the wax paper.. if the paper turns left or right.. Wah LA! that will tell you what it's doing.
Best
Brian

Sounds like an interesting idea. I will have to try that some time.
One possible issue about using this as an indicator of gear alignment...
The tapered rod gear legs on RV's (except RV-8) cause the wheel alignment to change with load. They are really only truly aligned at a certain load value. If you check the alignment with a reduced fuel load and no other payload in the airplane the wheel alignment will appear incorrect.

The advice I always give to new RV pilots that are concerned about tire wear is that your second set typically lasts three times longer than the first set.
You begin to learn to slow the airplane down to a more proper touchdown speed, you learn to maneuver on the ground without so much brake usage (this helps prolong brake life also) and the biggy is that you stop doing so many landings per hour of flight time (new RV pilots/owners usually do a lot of T&go landings when they first start flying there RV).

BTW the left tire outboard edge is a common wear location in the side by side RV's, because when new to the airplane and feeling for the runway (while still going fast) we tend to touch down first on the side we are sitting on / looking out of.

...Though I will admit that your tire life seems to be about the shortest I have heard of, it could still be caused by factors that I mentioned above.
I would try another set of tires and while the wheels are off for the tire replacement it will be easy to check the axle alignment.