Tires and UV rays

[Chris Z]

My trailer is underneath the carport we built last year until the next trip (hopefully soon!) but meanwhile a question about tires.
One tire is underneath next to garage block wall so it will never get direct sunlight while there although there is plenty of light. The other can get morning sun but that's all.
Probably won't get 2 - 5000 miles each year. Should I bother with buying covers and covering the tires while parked here? Maybe just put something over the one which gets some AM sun?
Thanks

[Chester Taje]

I would just put a junk piece of plywood by exposed tire.

[Steve L.]

It depends.

Everybody has a horse in this race. Tire cover manufacturers want to sell covers. Tire manufacturers want to sell tires. Hard to find an "official" opinion you can trust.

The Rubber Manf. Assn. offers a tire card brochure you can download for free. They suggest a cover.

RMA RV Tire Booklet

But, it depends.

If one lived in the southwest, all those sunny days, sun high overhead... Your tires would probably bake to a crisp long before you ever wore them out.

If one lived in Los Angles, the ozone would probably rot the sidewalls long before they wore out. I suppose things are better now, but one of our proveout tests involved putting tires on the roof the Los Angles plant and observing them after 6 months.

Heck, if one lived in the Pacific NW, your tires might mildew before they wore out.

There's no doubt that a cover will block nearly all the UV. Chester's suggestion will work too. I suspect you're really wondering if you can make the tires last longer before you have to replace them or perhaps if using a cover will protect you from some other failure.

Well, it depends.

Some manufacturers build 'ST" type tires with additional anti-ozonants on the assumption they will be out there longer than a "normal" tire. Others don't.

Will a cover help. Sure. Enough so that you'll notice? Who knows.

Here's something I do know. I store the trailer in my backyard in an east/west orientation. All the decals on the south side (curb side in my case) curled and peeled off. All the decals on the north side are still pristine. I blame the UV.

I bought covers. However, I plan to replace my tires, probably this summer. They only have about 12,000 miles on them with plenty of tread left but the tires are 4 years old. But then, that's just me.

[Pete Dumbleton]

Steve, as long as this thread is open, for the archival value, please add a short discourse on carbon migration with tire use and storage on earth or concrete or a piece of wood.

[Steve L.]

Steve, as long as this thread is open, for the archival value, please add a short discourse on carbon migration with tire use and storage on earth or concrete or a piece of wood.

Well, I'm not a compounder (or confounder as we used to call them) by training. My tire company years (17) were related to physical construction features and the consequences on performance. However, I occasionally date one of our former chemists and I know that what most migrates are the anti-ozonant oils. They are what makes that brown stain tires leave on the floor and in cheaper tires the brown stain along the edge of the whitewall stripe or letters. (Can't you just imagine how lively the conversation must be between two tire engineers on date? Paaarrrrteee!)

When the anti-ozanant is gone, the rubber starts to "check" or craze on the surface. When it's really gone, you'll start to see the very thin cracks, frequently seen low on the tire sidewall near the rim, or in the bottom of the grooves in the tread. (I have no advice with respect to the durability of a tire with these cracks.)

As a tire company, we had no use for the tire dressings used to make the tire look "wet". As much as anything, it's the air pressure forcing the oils to move towards the outer surface and the dressing isn't going to buck that force.

Tubeless tires lose, and this is a very loose approximation, between 1/2% to 1-1/2% of their air pressure per month. The method of loss varies from the slight "burping" out of the air from beneath the beads of the tire as the tire sidewalls flex, to just plain osmosis through the sidewall. The osmosis thing is going on all the time, moving or parked.

Carbon is usually pretty much locked up with the rubber during the vulcanization process and I don't think it goes anywhere.

We (the tire company, I'm not using the royal "we"!)) had no advice with respect to the earth/concrete thing. At the risk of offending someone, I put that in the same classification of storing batteries on the ground vs. a wooden board: Used be true, in the olden days, no longer makes a difference.

[Loren G. Hedahl]

Steve, as long as this thread is open, for the archival value, please add a short discourse on carbon migration with tire use and storage on earth or concrete or a piece of wood.

Also, be sure to include, for informational purposes, a section on how moss grows on mildew build-up and how the mildew/moss build-up might actually inhibit carbon migration. (Or is "exhibit" a better word to use in this application?)

Loren

[Steve L.]

Also, be sure to include, for informational purposes, a section on how moss grows on mildew build-up and how the mildew/moss build-up might actually inhibit carbon migration. (Or is "exhibit" a better word to use in this application?)

Loren

(Obscure reference follows
I suppose Moss build-up would have something to do with public relations for some British actress, or perhaps her alleged cocaine habit. Or perhaps something to do with tyres. But I only deal in good ole tires.

[Dan Meyer]

I don't cover my tires. The first set lasted 5 years, and cost me $100 to replace.

$20 per year isn't something to get worried about.

-- Dan Meyer

[Donna D.]

I bought tire covers and use them, although just about anything would work as long as it blocks the sun. AND I suppose it would depend upon where one lives and parks the trailer. We're so grateful to see the sun here in the Pacific NorthWET, premature aging of the tires isn't a major concern.

What I might worry about is premature aging...when the trailer is under tow...things like blowouts due to aging, etc. Okay so, I wonder if I can get a cover for myself...to prevent premature aging

[Pete Dumbleton]

OK, my point on carbon migration (I thought I got this from Steve, but it must have been another tire company guy on another RV group) is that as the tires flex in use, the carbon installed in the manf process slowly makes its way to the surface, providing protection over the life of the tire -- With tires that sit a lot and don't get used enough, the carbon stays inside and doesn't get to provide the protection. That simple.

I know when I put a truck in storage (in a carport floored with relatively dry sand) for six years, there was a lot of checking on the sidewalls, but no visible tread damage -- After a few thousand miles, the sidewalls started peeling so I replaced the tires.

I still have a utility trailer stored outside on sand in FL, with the tires now on boards, mostly to keep them from sinking into the sand... They are in shade, so I am not particulary worried about UV and ozone is everywhere.

[Chris Z]

Very interesting. Thanks
One more:
What about the spare on the back that I have covered always and still has the sticker on it? Just leave it there and keep replacing the other two or rotate or what?
Thanks
I'm tired now.

[Steve L.]

Sorry, Pete, but I'm not on board with the carbon migration that someone was promoting.

Ozone in the atmosphere is pretty much caused by the UV in sunlight. Anti-ozonant migration is facilitated by higher temperatures. Ozone gets everywhere.

To keep our geeky propellor beanies up to speed, here's a pretty good article:
http://goliath.ecnext.com/coms2/summary_0199-806271_ITM

The article does mention carbon atoms attached to the waxes in antiozonants, but it's clearly not the carbon doing the sidewall protection.

[Dan Meyer]

The biggest thing to remember about your spare is to check the air pressure. After all, a spare tire that has no (or low...) air pressure will be of no use in an emergency.

-- Dan Meyer

[Brian B-P]

...What about the spare on the back that I have covered always and still has the sticker on it? Just leave it there and keep replacing the other two or rotate or what?

Since tires apparently die from age even with a cover, it makes sense to me to rotate the spare in with the other two. That also ensure that you have a matching set when you need to use the spare... and it's more likely to have air!

My Boler has an antique spare which is not even exactly the same size as the ones on the axle, because they didn't make that size when the other two were bought, and those ones are too old. I intend to replace all three together and start rotating their positions.