Tire Problem, and Wheel Shimmy

[RFazio]

I've always had a slight wheel shimmy on the mains of my RV-6. When I put new tires on it would be better for a while then get progressively worse. I finally installed the wood stiffeners and that helped. Lately it's been getting bad again. When I applied the brakes it would get real bad. I thought I warped the rotors. so today I finally pulled the wheel pants and removed the brakes. I jacked up the plane and spun the wheel so I could maybe see if it looked like the rotors were warped. I could not believe what I saw the tire was out of round by about a 1/2 inch. At first I thought it was because it was sitting on that spot and it made a flat spot, but no that wasn't even where it was sitting. These are Michelin Aviator tires. They were not abused in any way. They are one year old. I thought I was doing good by buying Michelin tires. The tires are not even halfway worn. I guess I have to change them, what is the consensus about tires. Which ones should I get. Anyone have any ideas about what tires might stay round! I can?t believe I?ve had this problem in my truck with crappy tires, not staying round. Now I?ve got egg shaped tires on the plane. I was about to get new rotors and maybe new wheels because I was so fed up with the shimmy.

[Stabird]

We have an RV6A and recently went thru a similar problem. The main tires were wearing heavy on the outer edge. The tire pressure was 28 psi So we rotated, greased and balanced the tires and set pressure at 38 psi. We encountered a sever resonance shake around 40 mph. At first we suspected the nose wheel was oscillating. With a video camera no oscillation was noted. Serviced the nose wheel and set breakout to 25 lbs+.
We jacked up the plane and noted high spots on both tires. The flat spots were about 1/4 inch. Installed new tires with 38 psi. Problem solved. We used Monster retreads.
Conclusion. The high tire pressure along with the flat spots set up a resonance. The original tire pressure of 28 psi did not induce the resonance.
Hope this helps.

Skybird

[Bavafa]

I had noticed the same thing on mine, specially the nose wheel. I believe this is as a result of just sitting even though I fly at least once a week. I don?t know if there is a remedy or type of tire that is less prone to that out of roundness.

Ironically, even the new tires are not perfectly round, but not nearly as bad when they are used for a while.

Maybe the solution would be to use cheaper tire but replace more frequently.

[GalinHdz]

Originally Posted by RFazio

I've always had a slight wheel shimmy on the mains of my RV-6. When I put new tires on it would be better for a while then get progressively worse. I finally installed the wood stiffeners and that helped. Lately it's been getting bad again. When I applied the brakes it would get real bad. I thought I warped the rotors. so today I finally pulled the wheel pants and removed the brakes. I jacked up the plane and spun the wheel so I could maybe see if it looked like the rotors were warped. I could not believe what I saw the tire was out of round by about a 1/2 inch. At first I thought it was because it was sitting on that spot and it made a flat spot, but no that wasn't even where it was sitting. These are Michelin Aviator tires. They were not abused in any way. They are one year old. I thought I was doing good by buying Michelin tires. The tires are not even halfway worn. I guess I have to change them, what is the consensus about tires. Which ones should I get. Anyone have any ideas about what tires might stay round! I can?t believe I?ve had this problem in my truck with crappy tires, not staying round. Now I?ve got egg shaped tires on the plane. I was about to get new rotors and maybe new wheels because I was so fed up with the shimmy.

FWIW: I use Monster Re-Treads and I have never had a problem with them. The best part is that they are significantly cheaper than new tires.