rim trouble

[stevemc]

While getting ready to load the plane into the trailer, noticed the right tire a little flat. Hooked up the air hose, and within seconds the rim exploded. The rim shattered and went everywhere, resulting in 2 broken wrist bones, 15 stitches and many bruises. The rim was a common 2 piece Izusa type. I had no idea this could happen. The tire has no damage, just the rim. I believe it had a fracture or crack. I will try to post a picture of the result later. I have been flying for 5 years and have never had any type of accident or trouble. Please do not offer any speculation about over inflation, tire pressure, etc. as it did not happen. My sole purpose in this post is to warn of the possibility of occurance. I do not want to see this happen to anyone else. The injuries, while not good, could have been much worse.

Steve.

[mignazito]

Izusa rims are limited to 30 psi MAX. The newer ones are now labled as such. I too had one explode in my shop. Luckily it was in a tire jig I had and hit the ceiling, not me. NEVER inflate a Azusa rim to over 30 PSI EVER, even to seat a tire. The tires are often rated for much higher pressures leading one to think the rim can take it. It cannot as more than one of us has learned.

Be advised.

[indoruwet]

Izusa rims are limited to 30 psi MAX. The newer ones are now labled as such. I too had one explode in my shop. Luckily it was in a tire jig I had and hit the ceiling, not me. NEVER inflate a Azusa rim to over 30 PSI EVER, even to seat a tire. The tires are often rated for much higher pressures leading one to think the rim can take it. It cannot as more than one of us has learned.
Be advised.
I only have them inflated to 20 PSIG.

[mignazito]

Some 8" tires are actually limited to 20 psig. The problem arises when a tire has a 55 or even 70 psig limit which I have seen on occassion. The wheels are not marked while the tire is. This can lead to a dangerous situation if the owner, not knowing the wheel limits, uses the tire limit.

The Azusa wheel pressure limit is not well known. Their newest 8" Tristar wheel is actually marked at 30 psig max.

These wheels are die cast and not all that strong. Be careful about inflating tires on Azusa rims. Installing a new tire sometimes requires "seating" the tire on the rim by overinflating it. You cannot do this with Azusa rims. If it won't seat, deflate it and put some rubber "glide" or soapy water on the rim and try again up to 30 psig max.

[indoruwet]

Why would one want to inflate to high pressures ?
maybe to limit friction/resistance on grass ?

[mignazito]

Like I said, to "seat" the tire on the rim. This is done often with car tires when mounting them. The excess pressure is then let out after the tire "pops" onto the rim. You cannot do this with an Azusa rim or at least not very much. i.e. A 30 psig pressure on a 20 psig tire is OK for seating. Thye might take a little overpressure, but they have been known to blowup. Be careful and measure pressures closely as you pressure up.

I like to run 350X8 tires at about 30 psig as they give very low rolling resistance. The tire is rated for 55 psig, but I run it at 30 because of the rim. I have tested rolling drag on many different tires and the 350X8s are the lowest drag practical tire I found for a PPC.

[stevemc]

Here are some pics of the result.

http://s336.photobucket.com/albums/n350/stevemc42/

I will be switching to a solid rim. Again, I believe the rim was weakened or cracked. It was definitely low and came apart almost immediately. I think that we may have too much confidence in manufacturers, partly due to the high cost of anything having to do with "aviation". These rims are very common. I now wonder about temp changes, leaving the machine trailered or outside in winter, etc. This could have happened on landing, another potential disaster. I don't mean to rant, but like the commercial says, you have a lot riding on your tires.

Fly safe,

Steve.

[mignazito]

Actually the Azusa "Spinner" 8" wheel is not an aviation product at all. Azusa Engineering is a Go Kart parts mfg. The wheel is used on go carts. True aviation wheels are VERY expensive. If a tire goes flat on one of these die cast wheels it can get damaged particularly if it runs on pavement.

There are some mfgs that make better wheels, but they will cost you a lot. Hegar makes some nice 6" wheels that are spun aluminum.

[lowpull]

Wow! Can't believe a tube type tire would do that. Seeing is believing.

I have commented before on these rims. Cast aluminum or pot metal? They don't have much integrity. Of course, we don't use much runway usually, so it don't matter too much.

Ouch! Glad that you still got your eyes. Thanks for the warning. Let us know if you find a good replacement.