Michelin Tires / Alcoa Wheels

[richard waters]

> Don't be afraid to challenge someone if you have a strong
> feeling on the other side of an issue. I do appreciate someone pointing out
> my mistakes because I can then learn something that might be valuable to me
> in the future. I have heard that some are hesitant to post things on the
> GMCnet because they are unsure whether what they heard or learned is correct.
> I encourage those people to get involved. No one is going to look down on
> anyone with less experience on the GMC. We all started at the same place.
>
> Emery Stora

Emery,
Good job with these reports!

One thing that has bothered me since last Fall after hearing Don's tire talk at
Forest City revolves around tire pressures. He recommends 50 and 50 PSI and it
seems that Cinnabar etc. recommends 75 and 80 PSI. He said something to the
effect that you want the tire pressure low so that they warm up and the oils etc.
will work themselves through out the rubber. That sounded like bunk to me
however, but I kept my mouth shut as is expected of "newbie" rally attendees.

I run my Goodyear G159s at 80 PSI. I meant to ask Don about that while I was in
Forest City, but never got around to it because I was having too much fun with
Mike Beaton and Tim Brown in the Gilbert's Steak House Mobile unit!

Has anyone talked about the wide difference in opinion of what pressure to run
our tires at?

Richard Waters
'76 PB (with G159s at 80PSI) Troy, MI

 

[philip l. stewart]

Emery,
Thanks so much for clearing things up on this issue for me. The information you
got from Don make more sense now that you've added the details. I'm not sure
that I'll be lowering the air pressure from 80 psi just yet since I don't have
any idea what load each wheel is carrying. I certainly don't want to go under
inflated just to get a potentially better wear pattern in the center. I wish it
were easier to get these coaches weighed. Thanks again for your efforts for us
all.
Phil Stewart
'76 Transmode, TN

> Phil, John, Tom & others who are using Michelin. I got together with Don
> Wirth this morning and had a long talk about his comments on the Michelin
> tires and on the use of Alcoa wheels with them.
>
> He said that today's Michelin XPS Rib is also one of his recommend tires.
> Michelin, Goodyear, Cooper, Bridgestone & Dunlop (all steel versions).
>
> He says that when he indicated that Michelin has been having troubles with
> their tire it was on older models and not on the ones currently produced. He
> says that they had a 4 layer tread and had quite a bit of tread separation
> problems. They changed this to a two layer tread and found that it was not
> strong enough. They now use three layers and the current production seems to
> be working without problems.
>
> As for the 6" width of the Alcoas and the 6-3/4 to 7 inch design of the XPS
> Rib, he said that they will crown (be a bit rounded) at the middle of the
> tread. Might have slightly more wear in the center with no harm to the tire
> but his biggest concern was that it would have less contact area with the
> road and would not provide as much "holding power" or traction. To
> alleviate this, he says that instead of using 70 or 80 pounds in the tire,
> the pressure should be lowered (keep it above the amount needed for your
> actual weight) so that it will help flatten the tread where it hits the road.
>
> So, this proves once again that it is important to question things that are
> posted to the GMCnet. I reported what Don actually said but we all say
> things and don't always realize the impact or tell all the background or all
> the details.
>
> I post enough things that every once in a while I make a typo or just flat
> out say something that is not right. Funny how a word or two will make such
> a difference. Don't be afraid to challenge someone if you have a strong
> feeling on the other side of an issue. I do appreciate someone pointing out
> my mistakes because I can then learn something that might be valuable to me
> in the future. I have heard that some are hesitant to post things on the
> GMCnet because they are unsure whether what they heard or learned is correct.
> I encourage those people to get involved. No one is going to look down on
> anyone with less experience on the GMC. We all started at the same place.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM

 

[john szalay]

>Phil, John, Tom & others who are using Michelin. I got together with Don
>Wirth this morning and had a long talk about his comments on the Michelin
>tires and on the use of Alcoa wheels with them.
>
>He said that today's Michelin XPS Rib is also one of his recommend tires.
>Mh
>As for the 6" width of the Alcoas and the 6-3/4 to 7 inch design of the XPS
>Rib, he said that they will crown (be a bit rounded) at the middle of the
>tread.

Just went and measured the width of an steel radial rim and its 6 inchs
on the bead . I run 60 PSI cold on the XPS tires. The only problems I have
had was with tire wear and that was because of my alignment problems after
the complete bogey rebuild, I had an alignment done by the COOP last summer
when we had the coach repainted. and I noticed no wear or tire cupping
on the drive home. (from FL to KY) so time will tell.

John & Brenda Szalay
Still in Ky, can't make it to Rayne.
73 GMC PD

 

[david l greenberg]

Way to go, Emery!

Dave Greenberg

> Phil, John, Tom & others who are using Michelin. I got together with
> Don
> Wirth this morning and had a long talk about his comments on the
> Michelin
> tires and on the use of Alcoa wheels with them.
>
> He said that today's Michelin XPS Rib is also one of his recommend
> tires.
> Michelin, Goodyear, Cooper, Bridgestone & Dunlop (all steel
> versions).
>
> He says that when he indicated that Michelin has been having
> troubles with
> their tire it was on older models and not on the ones currently
> produced. He
> says that they had a 4 layer tread and had quite a bit of tread
> separation
> problems. They changed this to a two layer tread and found that it
> was not
> strong enough. They now use three layers and the current production
> seems to
> be working without problems.
>
> As for the 6" width of the Alcoas and the 6-3/4 to 7 inch design of
> the XPS
> Rib, he said that they will crown (be a bit rounded) at the middle
> of the
> tread. Might have slightly more wear in the center with no harm to
> the tire
> but his biggest concern was that it would have less contact area
> with the
> road and would not provide as much "holding power" or traction. To
>
> alleviate this, he says that instead of using 70 or 80 pounds in the
> tire,
> the pressure should be lowered (keep it above the amount needed for
> your
> actual weight) so that it will help flatten the tread where it hits
> the road.
>
> So, this proves once again that it is important to question things
> that are
> posted to the GMCnet. I reported what Don actually said but we all
> say
> things and don't always realize the impact or tell all the
> background or all
> the details.
>
> I post enough things that every once in a while I make a typo or
> just flat
> out say something that is not right. Funny how a word or two will
> make such
> a difference. Don't be afraid to challenge someone if you have a
> strong
> feeling on the other side of an issue. I do appreciate someone
> pointing out
> my mistakes because I can then learn something that might be
> valuable to me
> in the future. I have heard that some are hesitant to post things
> on the
> GMCnet because they are unsure whether what they heard or learned is
> correct.
> I encourage those people to get involved. No one is going to look
> down on
> anyone with less experience on the GMC. We all started at the same
> place.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM

http://www.gmcss.com/registry.htm

 

[david l greenberg]

> On the sidewall of the tires, the manufacture recommends the amount
> of pressure that should be in the tire.
>
> Get you coach weighted and go according to manufactures
> specifications.

I believe the pressure indicated on the tire sidewall is max. The
recommended pressure is on a decal to the left of the driver's seat or in
the operator's manual. HOWEVER, the recommended pressures are cold
readings and based on normal loading. As Ed states, get your coach
weighed and adjust tire pressure accordingly.

Most RVs sit for long periods of time and then are run at worst
conditions for short periods of time. Our GMC tires are probably at
extreme conditions just parking and turning. My gut feel is that running
tires above or below the recommended pressure for the load your coach
carries is not a good idea and will lead to problems.
David Lee Greenberg
GMC Motorhome Registry
Dedicated To The Preservation Of The GMC Classic!
www.gmcss.com/registry.htm

 

[david l greenberg]

> recommended pressure is on a decal to the left of the driver's seat
> or in
> the operator's manual. HOWEVER, the recommended pressures are cold
> readings and based on normal loading >>
>
> Yes, Dave, it usually is MAX and that is certainly true with
automobile tires
> that the info printed on the sidewall is the maximum pressure --
> however, someone reported that there is a difference for truck (and
light truck) tires.

Thanks, Emery.
>
David Lee Greenberg
GMC Motorhome Registry
Dedicated to the preservation of the Classic GMC
http://www.gmcss.com/registry.htm