Rubber preservation

   / Rubber preservation #1  

gbick

Silver Member
Joined
Jan 7, 2004
Messages
109
Location
Greenbush, Maine
Tractor
04 JD 4310 ehydro
I recently retrieved 4 tires out of my shed to find two of them deflated. When inflating them, I could hear hissing-through the sidewalls!! They were rotted and cracked. When I put these (used one winter) studded snows away about 9 years ago, they were inflated and treated with either Armorall or spray silicon. The shed is open-front so they were placed against the back wall,out of direct sunlight. Ironically, my occasionly driven '90 Nissan truck(58K miles) has it's ORIGINAL Firestones. Yes, their sidewalls are cracked, but they don't leak and have inspectable tread. The truck is kept in a carport. Over the years, I may have once or twice sprayed the tires. Every spring, I religiously wash under the truck and spray all the rubber-like parts(CV boots, engine and body mounts, etc., which would be a hassle to replace) with either Armorall or spray silicon. Both are preservatives, right? Well, maybe not. I seem to remember from the Michelin website that they do not recommend putting anything on their tires. I don't care about making these parts pretty (who said tires were supposed to be shiny, anyway?) I just want these parts to last. Have I been wasting my time and money under my truck with a spray can - or worse, actually harming these rubber components?
 
   / Rubber preservation #2  
I never use any of those products because I have heard they dry the rubber. But 9 years, I'd suspect a lousy batch of tires. My 1910 has original rubber for about 22 years and still looks good. I have several trailers with 10 year old tires that stay out half the year and still seem OK.
 
   / Rubber preservation #3  
ArmorAll is not your friend. It will cause the rubber to dry out. On the other hand, if you want "purty" dust magnet tires, go for it.

I don't have a technical answer about how some tires don't store as well as others. I'm sure it has to do with pure rubber content, maybe someone can give a technical response?? I have a pair of tires on my wood splitter that came from the factory on a 1980 Dodge D-50 pickup. One of them needs air a couple times a year, the other hasn't had air added since I put it on the splitter 7 years ago. Go figure. :)
 
   / Rubber preservation #4  
You avoided one major killer of tires ... the sun. Contrary to popular belief, Armorall and its companions do no good for rubber and often speed the dry-out process (unless you keep them coated every couple of weeks). The last killer is lack of "exercise" -- seriously, the reason people have much older tires on stuff they use than what survives in storage is that rubber needs to be flexed. Lack of flexion allows the lighter semi-liquid components to migrate to the surface and evaporate more quickly. That's why you seldom see more than surface sun rot on very old tires that are in use all the time, but newer tires that are left to sit will dry clear through.

VistanTN
 
   / Rubber preservation #5  
Most studded tires I've seen are 1 ply sidewalls. Most respectabel truck tires are at least 2 ply sidewalls. That would give you twice the thickness to begin with and might explain why the last longer.
 
   / Rubber preservation #6  
VistanTN said:
You avoided one major killer of tires ... the sun. Contrary to popular belief, Armorall and its companions do no good for rubber and often speed the dry-out process (unless you keep them coated every couple of weeks). The last killer is lack of "exercise" -- seriously, the reason people have much older tires on stuff they use than what survives in storage is that rubber needs to be flexed. Lack of flexion allows the lighter semi-liquid components to migrate to the surface and evaporate more quickly. That's why you seldom see more than surface sun rot on very old tires that are in use all the time, but newer tires that are left to sit will dry clear through.

VistanTN

I think that is very true. Seems to be similarly true with things like vinyl. A car left sitting with the windows up for a long period of time will certainly suffer more decay than one that is used all the time. As for the sun, you see a lot of travel trailers and motor homes with their tires covered from sunlight while parked outside. Good point.
 
   / Rubber preservation #7  
There are many different types of rubber. Most tires are made of blends of synthetic rubbers and natural rubber. Natural rubber is very abrasion resistant but has little resistance to oils, sunlight or ozone. Styrene butydiene rubber is the synthetic rubber that makes up most of the tire. It's properties are similar to natural rubber. Other rubbers used are: EPDM, a synthetic that offers outstanding weather resistance. Butyl; another synthetic that is resistant to passage of air molecules. Butyl is responsible for our not having to air up tires every few weeks as was the case 35 years ago when natural rubber was used for inner tubes. I'm sure some of you guys remember (Dad's car). A variety of materials are added to the base rubbers to create a compound with specific characteristics. Waxes and protectants are added to SBR that slowly bleed to the surface and protect from weathering. Carbon black is added to provide a solid material that is exposed as the rubber is eroded. This essentially creates a series of microscopic "Parasols" to keep the sunlight from shining on the rubber molecules. When chemicals are put on the tire, the waxes and the exposed layer of carbon black may be removed. This exposes the rubber to the elements and can increase the rate of degradation. When a tire is flexed for long periods of time the rubber degrades on the surface exposing the carbon black particlees as planed. The flexed position causes the carbon black particles to be pulled apart slightly, allowing the sun to hit the next "layer" of rubber. This layer erodes, exposes more carbon black which again pulls apart and the cycle continues until huge crack results. Tires that are used become warm internally which speeds up the rate of wax "blooming" or migrating to the surface. They tend not to crack as quickly for that reason. Note: different rubber compounds have different amounts of resistance to the elements. Not all rubbers or tires are the same.
 
   / Rubber preservation #8  
What I have heard is that tires are starting to deteriorate and become unsafe after about 7 years, irrespective of the tread depth and condition. I have some low mileage vehicles and my tires "rot off" before they wear out. I am repetitively faces with deciding when to stop using what would, except for age and cracking sidewalls, be generally a good tire.

I have used a brush-on tire preservative that I bought at Camping World. It protects against UV and Ozone, the two big non-wear related killers of tires. It costs way more than Armorall and doesn't have a cute Viking mascot but it works. I put on a set (6) Michelin steel belted radials (M&S tread) in 19.5 inch size in '97 and they are showing very little crazing on the sidewalls. Much less than I would have expected by now. They have about 70K miles on them and are good for plenty more. Had I not used the tire protectant they may have been replaced already. I think the UV/ozone protectant was well worth the price as it has extended the sidewall life so I can have a chance to use up more of the tread before the tire gets too cracked on the sidewalls.

Your mileage may vary...

Pat
 
   / Rubber preservation #10  
Concerning the life of a tire in storage, In the tire plant where I work we destroy any tires over two years old and our company scraps any over three years old in the warehouses and the delivery system is such that tires at the dealers are not that old. A three year old tire bought by a customer would in most cases be worn out by the time it is seven years old.
 
 
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