Tires/Wheels

[leland l garland]

[ADMIN note - This post was multipart/HTML. Please post in "plain text"
only. Patrick]

I purchased a GMC Eleganza this past summer -- one of the selling points
was that it had six brand new Goodyear steel belted tires. I have been
browsing the archives here and read something about mounting radial
tires only on wheels stamped 'radial' so I removed one wheel and cannot
find any evidence that it is a radial wheel. I assume all other wheels
also are non-radial. My question is: what are the risks of continuing
to drive the coach with this tire/wheel combination. (I have driven the
coach less than 50 miles at less than 40 mph since purchasing it.)

Thanks, Lee '75 Eleganza=20

 

[hdavis]

>
>[ADMIN note - This post was multipart/HTML. Please post in "plain text"
>only. Patrick]
>
>I purchased a GMC Eleganza this past summer -- one of the selling points
>was that it had six brand new Goodyear steel belted tires. I have been
>browsing the archives here and read something about mounting radial
>tires only on wheels stamped 'radial' so I removed one wheel and cannot
>find any evidence that it is a radial wheel. I assume all other wheels
>also are non-radial. My question is: what are the risks of continuing
>to drive the coach with this tire/wheel combination. (I have driven the
>coach less than 50 miles at less than 40 mph since purchasing it.)
>

Lee,

Did you remove the tire from the wheel and look on the inside? If the wheels are not radial-rated, using radial tires can flex
the wheels and cause them to mechanically separate in a catastrophic failure. In theory, all GMCs manufactured beginning in
1976 came with the radial wheels. However, it was pretty common (according to some folks who serviced these things) to
exchange a tire/wheel combination when a tire went flat (in order to save time). So, it's possible to have non-radial wheels
on a coach that originally had radial wheels on it.

Good luck,

Henry

Henry Davis Consulting, Inc / new product consulting
PO Box 1270 / product readiness reviews
Soquel, Ca 95073 / IP reviews
ph: (408) 462-5199 / full service marketing
fax: (408) 462-5198
http://www.henry-davis.com

 

[balcom robin s]

Lee:

I'm no expert, but I'll share what I've learned the past 4-5 months looking
at thirty or forty GMC wheels.

A radial tire on a bias rim will crack the rim. I think a post on this forum
a while ago explained why. The crack develops in the area of the weld bead
connecting the center part of the wheel to the rim. I've come across three
rims that have been cracked like this. All three were bias rims with radial
tires. One I found when I had to keep putting air in a slow leaking tire -
the leak was because of the cracked rim. The other two were bias rims that
had cracked, then someone tried to repair them by welding them and
installing a tube. I've had no personal experience with a catastrophic
failure from cracks such as this, but I don't think it's something I'd want
to gamble on.

The one structural difference that I know of is the radial rim has a
stronger weld bead - there may be other differences that I'm not aware of.

You can tell which rims you have without taking the tire off the wheel. In
fact, you can tell if you have a bias rim without even taking the wheel off
the motorhome. After you've looked at enough of each type, you'll be able to
spot which is which by looking at the weld bead through one of the four
large openings in the rim, without taking the wheel off the vehicle, or
scraping any paint.

Bias rims have "27604" stamped on the face of the wheel, between two
lugnuts. The two lugnuts are the two that are closest to the valve stem. You
may need to scrape away some paint to see the numbers. They're stamped with
3/16" stamps (I think), so the five numbers end up being about 3/4" long.

Radial rims have "27995" stamped on the inside of the rim. To see these
numbers, you have to take the wheel off the motorhome (no need to take the
tire off the rim!). What I mean by the inside of the rim is the surface
where grease gets when the ball joints are filled too full of grease, and
some gets out and drops onto the inside of the rim. So, you may need to
scrape grease as well as paint to see these numbers. The numbers will not be
on the "ledge" where the weld bead is, but rather on the next ledge down,
along with other information such as max. load rating, etc. On older radial
rims, you will also find "RADIAL" stamped on the same ledge. Some newer
radial rims don't have the "RADIAL" stamp, but I did see an "R" in a circle,
which may signify it's a radial rim. I found no radial rim that had the part
number stamped on the face where the bias rims are stamped.

This information deals only with the 16.5 inch rims. I've had no experience
at all with the 16 inch rims.

Good luck!

Robin - '73 Sequoia - Corning, NY

 

[david l greenberg]

>
>I purchased a GMC Eleganza this past summer -- one of the selling
>points
>was that it had six brand new Goodyear steel belted tires. I have
>been
>browsing the archives here and read something about mounting radial
>tires only on wheels stamped 'radial' so I removed one wheel and
>cannot
>find any evidence that it is a radial wheel. I assume all other
>wheels
>also are non-radial. My question is: what are the risks of continuing
>
>to drive the coach with this tire/wheel combination. (I have driven
>the
>coach less than 50 miles at less than 40 mph since purchasing it.)
>
>Thanks, Lee '75 Eleganza=20
>
Personally I think the risk is worse to a tireman repairing the tire or
remounting it 'cause they have been known to blow and have caused serious
injury or death.

I am uncertain about the risk in driving with them but I wouldn't do it.
Especially in a place like Arizona whre the ground temp tends to send
wheel and tire temps soaring.

If the wheels are not stamped "radial" on the inside surface, be careful.
If someone is injured repairing your tire/wheel combination, and you had
prior knowledge of this condition (in my humble opinion) you may be found
to have liability. (you should probably erase this note!)

The simple solution if your wheels are for bias ply tires is to invest in
new "R" wheels. If you had old tires I would say, bite the bullet and buy
16" Alcoa aluminum wheels and new tires to match.

Regards,

Dave Greenberg
GMC Motorhome Registry
200 MacFarlane Dr PH4
Delray Beach, FL 33483-6829

 

[hdavis]

>
>>
>
>If the wheels are not stamped "radial" on the inside surface, be careful.
>If someone is injured repairing your tire/wheel combination, and you had
>prior knowledge of this condition (in my humble opinion) you may be found
>to have liability. (you should probably erase this note!)
>
>The simple solution if your wheels are for bias ply tires is to invest in
>new "R" wheels. If you had old tires I would say, bite the bullet and buy
>16" Alcoa aluminum wheels and new tires to match.
>

We had the decision to go to Alcoas made for us - 2 of the 7 wheels on our coach were non-radial and I wanted the extra safety
margin in the weight specification. The often repeated rumor of the demise of 16.5 tires was not a factor since the local
school busses all run 16.5 load range E. Replacement on the road might be a different story though.

There's a number of opinions about whether or not to replace the wheel studs with the longer version. I had ours replaced
based solely on Wes Coughlin's recommendation when going to the Alcoa wheel. I'm glad that I did because several fo the studs
had micro fractures that were not visible from a simple external inspection, or had some elongation from over-torqueing. The
small number of fractures alone would not have concerned me that much, but for a few bucks a piece I'd just as soon not be
concerned at all about the stud's condition.

Henry

Henry Davis Consulting, Inc / new product consulting
PO Box 1270 / product readiness reviews
Soquel, Ca 95073 / IP reviews
ph: (408) 462-5199 / full service marketing
fax: (408) 462-5198
http://www.henry-davis.com

 

[hdavis]

>
>
>Bias rims have "27604" stamped on the face of the wheel, between two
>lugnuts. The two lugnuts are the two that are closest to the valve stem. You
>may need to scrape away some paint to see the numbers. They're stamped with
>3/16" stamps (I think), so the five numbers end up being about 3/4" long.
>
>Radial rims have "27995" stamped on the inside of the rim. To see these
>numbers, you have to take the wheel off the motorhome (no need to take the
>tire off the rim!). What I mean by the inside of the rim is the surface
>where grease gets when the ball joints are filled too full of grease, and
>some gets out and drops onto the inside of the rim. So, you may need to
>scrape grease as well as paint to see these numbers. The numbers will not be
>on the "ledge" where the weld bead is, but rather on the next ledge down,
>along with other information such as max. load rating, etc. On older radial
>rims, you will also find "RADIAL" stamped on the same ledge. Some newer
>radial rims don't have the "RADIAL" stamp, but I did see an "R" in a circle,
>which may signify it's a radial rim. I found no radial rim that had the part
>number stamped on the face where the bias rims are stamped.
>

For what it's worth, my wheels had NO numbers stamped on the outside (either face). All numbers were covered by the tire - on
the inside. Paint on the inside obscured some stampings.

Henry

Henry Davis Consulting, Inc / new product consulting
PO Box 1270 / product readiness reviews
Soquel, Ca 95073 / IP reviews
ph: (408) 462-5199 / full service marketing
fax: (408) 462-5198
http://www.henry-davis.com