[A/S] multi part rims and gross stupidity

[john dorsey <jrdorsey@xxxxxxxxxx>]

OK first the multi part rims, then I'll talk about the gross stupidity.

We should be clear about terminology, there are several types of multi
piece rims, some are inherently dangerous and some are not. 

There are three major types;

Center locks
split rings
lock rings

The first time a saw a center lock rim I said who's the dumb*ss that
designed this! These where dangerous when knew and illegal now. On this
type the rim separates about in the center into two about equal
sections. These where common on 2 to 5 ton trucks in the 50's 60's and
70's. When you hear of some one getting killed these are usually the
culprits. There is a hefty fine in most states for installing tires on
these. They have been known to come apart going down the road or just
sitting someplace. when I started as a mechanic these were legal and hated.

Split rings are the most common type of multi piece rim, there are
probably millions of these on the road today. around here most all of
our fruit trailers use these. On these the outer lip of the rim is a
ring that is split and removable. There is a tapered groove that
interlocks the ring to the rim, the tire pressure forces the ring to
seat tighter in the rim. These can be dangerous if the ring is bent,
worn or dirty, the rim is bent, worn or dirty, or improperly assembled.
Usually if these are going to blow it's when they are first inflated,
I've never heard of one of these blowing going down the road.

Lock rings are the safest type of multi piece that i know of. The outer
rim is a one piece removable ring held in place with a split lock ring
that snaps onto the inner rim. These can also be dangerous if the ring
is bent, worn or dirty, or either rim piece is bent, worn or dirty, or
improperly assembled.

I would not recommend anyone change these at home unless experienced
with them. The shop I worked at did not have a safety cage, we would put
the rim under the lift rack and use a clip on chuck to inflate it from
outside. All it takes is one mistake and your dead. The one and only
center lock I did, I rolled it about 100 ft out back and inflated it
from inside the garage holding my breath the whole time.

Now the Stupidity. Even one piece rims are not safe if you don't have a
clue what you are doing. We had a local family that "found" a tire and
mounted it on their rim by themselves. The only problem was that none of
them could read and didn't know that the tire was a 16.5 while the rim
was a 16. They lived behind a tire store so they rolled it over there
and inflated it. The father got a helicopter ride to the trauma center
and his arm reattached, while the son only lost a finger. The funny part
is they later sued the tire shop for leaving an air hose out where they
could get to it :-)