8.00 x 6 tire pressure

[8466]

I have 8.0 x 6 tires on my 140. The POH only gives 6.0 x 6 recommended tire pressure. Does anyone know what the recomended tire pressure is on the 8.0 x 6 tie is?

Thayne

[6863]

Thayne, I do not know what the recommended pressure is but on my 8.00 X 6s I run anywhere from 15 to 30 psi depending on what kind of surface I want to use. 30 psi seems like a good everyday pressure. I have run as low as 5 psi but found that the tires were slipping on the rim which threatened to cut through the valve stem which of course would be bad. Because I sometimes run low pressures I have painted yellow slippage marks on the tires opposite a slippage mark on the hub cap.

[6643]

Technically, the pressure should be lower than for the 6.00 tire. What happens is the load on the tire is distributed over the contact patch of the tire, so, if you have 20 psi and a 400 lb load, your contact patch will be 400/20 or 20 square inches. If you increase the pressure to 25 psi the tire will "round up" until the contact patch is 400/25, or 16 square inches. At 40 PSI you're down to 10 square inches on the ground.

Doesn't help, does it?

I agree, put witness marks on them. A sheared off valve could ruin your day.

Oh, the original question... There is no recommendation. If you can find a plane with similar loading that has a spec for those tires that would put you in the ball park. You can use the same math to figure out the size of the contact patch they're aiming at and back into the right pressure for your application.