Tire pressure for the the 15x6.00x6 tires

MSFT-1 · #1 08-31-2009, 12:58 PM

I spoke to the manufacturer?s rep for Air Hawk tires today.

He mentioned that the recommended pressure for the 15x6.00x6 tires is 68 psi. He explained that it is a low squat tire and is designed for much higher pressures than a 6.00x6 tire (which is typically supposed to be at 42psi). I currently have 35 psi in them so I was pretty surprised by his comments.

He further said that all tubes by major manufacturers are the same now. Air Hawk was the last to switch away from natural rubber to butyl rubber (about 5 years ago). He said stories of people needing to put air in their tires monthly indicate a problem like a leaking valve.

I am wondering what pressure other people are using for the main gear tires on the RV10s (and other RVs for that matter).

BTW, can you tell I am doing the annual based on the number of maintenance related posts in the last few days?

MSFT-1 · #2 08-31-2009, 02:40 PM

I just read the tire specification manual from GoodYear. It confirms 68 psi for that tire.

TSwezey · #3 08-31-2009, 03:43 PM

I was asking the same question at Osh. I had been running with 45 then someone told me 60 now 68 wow! I am replacing my tires this week so 68 it will be. Now what about the front one?

MSFT-1 · #4 08-31-2009, 03:49 PM

Here is the resource I mentioned.

It says that the nose gear tire uses either 31 or 50 psi depending on whether it is 4 ply rated or 6 ply rated.

As stated before the 6 ply rated main gear tires for the RV-10 should be at 68psi.

TSwezey · #5 08-31-2009, 03:53 PM

Thanks. I have the front at 50.

chunt0 · #6 08-31-2009, 09:39 PM

You might want to check the documentation that came with your wheels. I think Cleveland recommends a maximum of 42 psi on the main wheels. The tire and wheel makers have different and conflicting design robustness and "keep our lawyers happy" requirements. They are not on the same page--maybe not even reading the same book! Cleveland's limits for the other RV models are even lower.

Dave Cole · #7 09-01-2009, 06:53 AM

The best tire pressure for any particular application isn't necessairly the tire's maximum inflation pressure. While the maximum pressure is correct for the maximum allowable tire load, applications at lower than maximum load should use lower than maxiumum pressure. If the inflation pressure is too high, the tire's ground contact area will be smaller than optimum which can adversly afffect braking, not to mention that the tire will be stiffer than you would probably want.

For example, assusme you have 1600 pounds on the mains, or 800 pounds on each tire. At 68 psi, the ground contact area will be appriximately 800/68=11.8 sq.in., which is equivlaent to a 3.4 x 3.4 patch on the ground. If you reduce the pressure by half to 34 psi, the ground contact area will double.

The correct pressure for you aircraft should be chosen by experimenting, but I believe that most RVs are inftated closer to 34 psi than to 68 psi. Van's RV-7 wheel and tire assembly instructions say to inflate to 25 psi, although they did not say that 25 was the optimum operating pressure.

TSwezey · #8 09-01-2009, 07:06 AM

With about 65 flying hours on my plane I can tell you the tires hate 45psi. There is nothing left of the outer tread. I am going to 60 psi at a minimum. The RV-10 is completely different beast compared to the other RV's.

MSFT-1 · #9 09-01-2009, 08:18 AM

Parker (Cleveland) tech support confirmed that they recommend a maximum of 42 psi.

He is going to go back to the engineers and point out that both Good Year and McCready recommend 68psi for the tire used on that rim. I am hoping for a call back within a day or so.

I clearly had the same problem with underinflation. The photos of under inflated tires shown in Good Year's tire manual might as well have been of my tires. The wear patterns were exactly the same.

As another poster suggested, I will experiment with different pressures to see what gives the best performance/feel etc. I will likely start at 50PSI.

JoeBlank · #10 09-01-2009, 10:14 AM

The tire pressures recommended by Vans take all of the above issues into account, including one other that hasn't been mentioned here yet. That is aircraft handling and gear leg excitement. If you run your tire pressures above what Vans recommends, then you may experience gear leg shimmy/vibration and other unknown handling issues. Lower tire pressures tend to dampen out the extra energy at the expense of some additional tire wear.