FastEagle wrote:
Tireman9 wrote:
You also are confusing the relationship between external visible sidewall cracking and the remainimg structural integrity of the internal components.
Common Tireman, I'm not confusing that any more than I would confuse the function of expander tube brakes with disc brakes.
We are talking tires here. Try and analyze what I said and what impact the unknown has on the subject. When something is injected to prevent something it often causes some side effects. Could the injection of ozone inhibitors designed to offset early tire cracking have a side effect on the same tires aging? That’s all I was writing about. I know there is a very low probability of any positive answers. It’s a discussion forum about tires. Does the ST tire suffer more from these injections than other tire designs? Would it help to explain the ST tires 3-5 year life expectancy?
I wonder what happens to such tire additives when they set unexercised for five or six months in the desert states during the summer months? Cracking on the top half of the tires and nice smooth sides on the lower half?
FastEagle
The anti ozone chemicals are mixed into the sidewall compound and to a lesser extent into the tread compound as those are the components exposed to Ozone. The compounds that are of primary concern for long term durability are those directly around the steel belts and at the ends of the belts. These are internal compounds and do not need the same protection from external Ozone.
So when I said "confusing" I may not have used the best word.
Sidewall cracking will get worse with time and heat. Belt compound rubber will loose its strength with time and temperature (remember the non linear relationship).
My point was that we are using a feature (cracking) of one component to try and predict the properties of a different component. While both see heat of operation and both see heat due to different ambients the external compounds also are affected by Ozone, UV, car wash chemicals and abrasion. The relationship is not exact.
I believe flight hours are one of the primary measures of the life of aircraft and if hours were the only unit you could record you would come up with some number and apply statistics to arrive at a confidence level that the aircraft should or should not be ok to fly. This works till you run into an unusual situation as seen with Aloha Airlines when the side of the fuselage blew out.
I do not believe the ST tires suffer more from the inclusion in anti-oxidants in their sidewall rubber. (I have no knowledge of and do not believe that all ST tire sidewalls have more AO than any other tires.
I do believe that ST tires suffer from abnormal side loading due to tandem axles and to higher loading than they can tolerate at the speeds they are operated at, compounded with demands that they be lower cost than many other tires. Just as TPMS were mandated on cars because drivers refused to check their tires so a good portion were driving at 20% to 40% low I would like to see all RVs have TPMS.
I would also like to see metal valves on all RVs. Rubber valves are rated 65 psi max cold but most RVs seem to come with low cost rubber valves even when the spec is 65 psi for zero reserve. How about speed limiters on the TV when the RV is hooked up?
Sorry got off topic but the answer is not as simple as many would like.
