Re: New to me 87 gv
Reply #37 –
While I am not a tire engineer it serms that moisture CAN transfer through the thin rubber coating over the steel cord belt as evidenced by the actual rusting that caused the failure. The moisture that caused the failure was not in the tire when made.
My memory of these 30 years ago same questions I asked after having seen multiple failed tires from rusted cord belts included a then current component of the constriction of the carcass that included a dry acid coating of some kind over the steel belts themselves to allow the rubber like coating to adhere to the belts better during the process.
I was told that Introduction of water vapor under heat and pressure into the tire over long enough activates the acid which speeds the rusting process.
Probably why our coaches all came from Foretravel with a DRY air full pressure air outlet installed when new.
Michrelin tires carcass are guaranteed for 7 years, 700,000 miles and three retreads from an authorized Michelin rebuilder.
As has been posted here the tires are designed to release an agent during use to promote a longer, non cracking life that we d9 not generate near as much of from our low mile use.
I,assume the same agent is present in the inner cord belts construction. If under used the inner carcass may not seal out water vapor as well over our much longer term use.
Adding non dry air or CO2 or Nitrogen would seem to be a contributor to our non commercial,uses issues with our tires.
The low miles of use and the extended years of use and the non release of the non cracking agents from the low use and then adding non dry air into the tires would seem to all match the observed failures..
I am only relaying the answers I remember from long ago so please if a current commercial tire engineer would like to comment I am all ears.
After explaining this to every purchaser of a motorhome from me or my staff I had no further rusted cord belt failures.
Or you can buy $4-5k plus sets of tires every five years versus hassle with using the built in coach air system.
My coach required replacing the oil soaked and weak from long use D2 valve to raise the coaches air pressure from 90-110 as received to 110-130 to fill the tires quicker and for stronger brakes.
My car tires are all nitrogen filled and I have a large tank in my shop I fill everything with.
Using the nitrogen on my sir tools stopped the rusting of the tools internally or I could run an air dryer from my 165 pound pressure compressor an add a oil luber for better sealing and wear reduction.
Our use does not match the truck tires design for crack prevention necessarily. Later tires seem to show less external cracking in the results posted here.
Unfortunately any internal issues are not visible without removal.
A removed tire with no internal rusting or damage visible that meets the tires external manufacturiers condition guidelines would seem to be useable safely for another set time?
You have to fill the tires without water vapor if you want a long term safe ride IMO.
Or buy tires much quicker and/or buy less expensive tires to help defray the accelerated costs....
Topic: New to me 87 gv