When mounting tires on the split-rim Matco wheels, it seems sometimes we get lucky and the first try seals air-tight and then at other times, at least one of the wheels always has a chronic leak!  Most install the wheel per Matco's directions with a generously-lubed (Vaseline or silicone paste) o-ring.  Some give up and install a tube, which adds more weight and $$$.

A couple of years ago, I installed 21" Aero Classic tires on my STOL 750's 6" main wheels and used the o-rings with no problems.  However, after about 18 months, the right main developed a chronic leak.  I tried a shot of "Slime" tire sealant and it fixed the leak, but the tire spins up enough at take-off to produce a shuddering vibration due to imbalance as the wheel lifts-off.  It's easy enough to stop it with a tap on the brake, but annoying and no one likes shuddering vibrations in an airplane!

I recently dismounted the tire, cleaned out the Slime, and generously lubed the o-ring and the groove it rests in when the wheel halves are bolted together.  Using soapy water to inspect, I persistently had a leak that I could see coming from where the wheel halves are joined, bubbling up from the hole in the wheel where the hub comes through.  Despite 3 attempts, it still leaked! (And yes, I did thoroughly clean the inside of the wheels and even buffed the mating surfaces with Scotchbrite in case there was a burr, etc. - I tried both 3M silicone paste grease and Vaseline for the lube.)

Finally, I tried applying a circle of a thin film of "Tite Seal" sealant, about 1/4" wide, to the inner faces of the wheels just outside the bolt circle but not on the groove where the o-ring will rest.  Tite Seal has now been re-branded as "Niel Seal" but it is the exact same product.  It is a thick sealant paste of a consistency similar to Pro Seal, but it is NOT an adhesive and is non-hardening and non-corrosive. (A lot of sealants are adhesive and it might make it tough to later separate the wheel halves.)

I lubed the o-ring with "EZ Turn" which is the same thing as "Fuel Lube.."  Not sure of the composition, but it looks and feels like a silicone paste grease but seemed a bit thicker than the 3M product.  After bolting the two wheel halves together, I also applied the EZ turn to the groove before pushing the o-ring off the rim and into the groove.

Finally, I had a good seal and no leaks!  I just happened to have both of these products on-hand but they are available from Aircraft Spruce and elsewhere,  Now, fingers crossed no mysterious leaks in 18 months! Ha!

John

N750A