UV protection for tires. Still important, and the facts haven't changed in 7 years

 This is a reprint of a post I did in 2014. The facts and data have not changed.

For some time I have been reading posts and advertisements about tire covers and UV protection. As an engineer I prefer FACTS over sales PR.

This investigation has taken more time than I originally wanted as I needed a reasonable way to measure UV and a day with full Sun.
 - Not something easy to find in NE Ohio-

As they say it all came together one day in April. While it was cold 24°F last night and we had an inch of snow yesterday, it is bright and sunny today with only a little haze in the sky.

The test uses a Hawk2 UV meter. This unit is intended to help you judge how much sun you are getting while at the beach but I felt it would serve my purposes as we are not trying to measure an absolute value in milliwatts per square centimeter but a gross relative level of shielding of different materials used to cover tires.
If interested you can learn more about UV HERE and more about the UV Index HERE

I set up a test using my RV.

As you can see the UV of 6 years here in Ohio,  has pretty much destroyed the cheap vinyl used by Coachmen for the side decoration. Anyway the front tire has my normal white vinyl tire cover and there is a standard blue tarp, a roll of window screen and some black cloth backed vinyl similar to what is used in black tire covers.

I will show the meter readings for each "shield".
Full Sun gives a reading of 9 which is considered "HIGH"

 while in full shade the reading in zero.

Under the white cover the reading is zero

 and even under the black cover the reading is zero

.

  but the screen only reduced the UVI to level 5

I interpret these results to indicate that anything that is not in direct sun or that shields all direct sunlight will provide adequate protection from UV damage for tires.

I would not be worried about reflected light going under the RV to the back side of the tires as this is full shade. After all, tires are designed to be outdoors and we are not trying to protect tires for 20 years but only to get past a normal vehicle usage of 4 to 5 years to the 8 to 10 year range for many RVs. I would not consider open mesh as used in some "tire covers" complete protection but it is probably better than nothing.

NOTE I did not address the effects of heat on tires in this post. I did cover in THIS post and that clearly shows that white covers are the ones to use if you want to keep your tires cooler so they age more slowly.

BOTTOM LINE
If you want to protect your tires to give you the longest life possible you need to cover them with white solid covers such as cloth backed vinyl being a most reasonable option.

##RVT1006

Tire "Dressing" and "do not use covers"! Where's the test data?

Been following a long thread on an RV Forum on the topic of "Tire Dressing" aka tire treatment or "Tire Shine".

The good news is that most posters knew to not use any product that contains Petroleum Distillate. Too bad some RV dealers don't follow the guidelines on this. I have seen a number of display coaches almost dripping with some slippery fluid. Might be Brake Fluid or even motor oil as the tires were shiny and I could scrape the coating off, leaving a "slimy" substance on my finger.

I saw a number of different products mentioned and many suggestions that a product called 303 was a good UV protectant.

I saw no one provide any actual direct comparison test data for any product that would support the claim of protection against UV damage. With a little work getting through the maze of retailers selling "303" I finally made contact with their customer service. I asked "Can you provide any test data on 303 vs other tire protection products. Also info on if 303 application removes any of the wax or oil or anti-ozone chemicals built into tires." The answer was that they would ask their chemists. This seems strange that a company making claims on the performance of their product would not have comparison data available that would back up and support the claim. Please note, I am not saying that 303 does not offer some "protection" against UV damage to tires. I am concerned that the actual application as seen on YouTube may be removing the special waxes and anti-ozinate chemicals tire companies put in our tires.

If I receive actual test data that compares 303 against other products that make similar claims I will post on this blog.

What was most concerning were a couple of posts where the writers claimed

"I got tired of reading all the opinions on tire dressing so went to the source, Michelin. They stated that washing tires with mild soap is the only thing they support on their tires, no dressing no covers, no nothing. You don't see shiny tires at a truck stop and these are the people who put on the miles."

Another said "Goodyear RV tire guide says. Just keep them clean, no dressings, no covers, zip. You can use the same stuff you wash your RV with perhaps use a medium brush on stubborn spots."

I responded:   Interesting comment on "no covers". Wonder what Goodyear RV guide you are looking at? 
I found in THIS Goodyear RV Tire Guide and under storage the advice to store tires "in sunless area" and "Don't store tires where they are subjected to direct sunlight or extreme temperatures".
Based on the above, how does telling us to not use tire covers make sense?

I have confirmed with actual test data that covering tires can reduce the tire temperature by about 40° F which could extent tire life by many months, depending on how long you protect them from artificial heat aging.

I checked and found just the opposite on the shielding from the Sun. In fact I even contacted an Engineer at Michelin and he said "Our position regarding tire dressing and protection has not changed. It is still recommended that tires are cleaned with a mild detergent and water, and they are protected from direct sunlight when the vehicle is parked for extended periods of time. This is usually accomplished with the use of some type of cover. "

So I don't know where the "no cover" info from either Goodyear or Michelin comes from and if you read my blog you know that this tire design engineer is a strong proponent of using White vinyl on Class-B & C tires and the flat mesh of any color on Class-A.

I have nothing against 303. I am wondering why, for the price they don't have any actual direct comparison performance data on UV protection.

PS. If you don't want to protect your tires from the heat aging due to sun exposure please don't ask me to explain why you don't get longer life from your tires. Also next time you run into someone selling an brand  "Tire Dressing" ask to see the test data and see what happens.

Question on UV & Ozone tire damage.

Got this question and thought I would share my answer
"Tireman,
First of all, thanks for all your informative comments here, and also for the mounds of useful information in your blogs.
Have a question though... I've always thought that damage to sidewalls from ozone (which is always in the atmosphere) is going to cause sidewall damage more quickly than UV rays. Therefore, unless your motorhome spends a significant amount of its life in direct sunlight (as it might if you were full-timing or even half-timing), it really doesn't matter much if you cover the tires, since you are going to be replacing them in 7 or 8 years anyway. Is this faulty thinking?"

Yes Ozone can do real damage to tires. I have seen sets destroy because they were parked in a garage that had a leaking Ozonator.  BUT Heat is the primary killer of tires.
Ozone and UV can only attack the rubber surface but heat damages the internal components and structure in addition to the surface rubber.
The UV protection test in the link above shows how almost anything can stop the UV damage to tires.

The stuff sold that promises UV protection is like suntan lotion in that it may extend the time you can be in the sun without getting burned but I know of no spray on protection that cuts UV to zero.

 Heat accelerates the degradation of the molecular bonds which can lead to belt and tread separations.

I did a test on covers

that shows the significant increase in tire temperature. Since the affect of heat DOUBLES with each increase in temperature of 18F this translates to an effective doubling of the "aging rate" of tires (or reducing the tire life).

I cover my tires whenever parked for more than an overnight stay where the tires can be exposed to direct sunlight. The WHITE covers block all the UV and keep the tires at about ambient temperature rather than baking the life out of them.

With proper care:
Washing with same cleaners and cloths I would use on the RV body.
Having the tires "under-loaded" by about 20% (a 20% Safety Factor if you like) when setting cold inflation.
Never getting lower that 5% above the inflation needed to carry the load.
Multi-axle trailers should run the tire "max" inflation unless they have significantly upgraded their tires with higher Load Range and larger size, but they still need to run a much larger "Safety Factor" due to the unique loading caused my their tandem axles.
Always running TPMS and checking pressure every AM and after each stop.
Using digital gauges that have been shown accurate to +/- 1psi.

I am hoping for 9-10 year life on my Motorhome. If I had a multi axle trailer and took the same precautions I would hope for 5 to 7 year life due to unique loading from suspension design.

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Tire Ozone protection

A question was asked about tires marketed as intended for "RV use" vs tires not marketed for RVs as it relates to both sidewall stiffness and UV protection.
   Tires made for use on US highways have a regulatory test they must pass. This "Rim roll off" test establishes the minimum side force a tire must resist before the tire comes off the wheel. Since it is the air pressure that carries the load, not the tire sidewall, two tires of same load capacity, size and inflation  will have very similar flexibility.

RE: Anti-Oxidants and Ozone and UV protection of rubber.

Unlike Sunglasses which can be tested for UV transmissivity, tire protection in done with internal chemicals.
Marketing claims of "More" or "Better" are in my opinion just PR as they never say better than what other tire. There is also an upper limit in the amount of these special chemicals tire companies can put in a rubber compound before other properties are negatively affected. There are also different chemicals that could be used. One tire company may choose chemical "A" and have 2% while another company may select Chemical "B" and use 1% but since chemical "B" is better then "A" less is needed for similar protection but "B" is probably more expensive.

I know of no recognized industry test that gives a meaningful comparison number for weathering and Ozone protection so it's impossible to compare different brands.

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UV Tire protection. The FACTS

For some time I have been reading posts and advertisements about tire covers and UV protection. As an engineer I prefer FACTS over sales PR.

This investigation has taken more time than I originally wanted as I needed a reasonable way to measure UV and a day with full Sun.
 - Not something easy to find in NE Ohio-

As they say it all came together today April 16 2014. While it was cold 24°F last night and we had an inch of snow yesterday, it is bright and sunny today with only a little haze in the sky.

The test uses a Hawk2 UV meter. This unit is intended to help you judge how much sun you are getting while at the beach but I felt it would serve my purposes as we are not trying to measure an absolute value in milliwatts per square centimeter but a gross relative level of shielding of different materials used to cover tires.
If interested you can learn more about UV HERE and more about the UV Index HERE

I set up a test using my RV.

As you can see the UV of 6 years here in Ohio,  has pretty much destroyed the cheap vinyl used by Coachmen for the side decoration. Anyway the front tire has my normal white vinyl tire cover and there is a standard blue tarp, a roll of window screen and some black cloth backed vinyl similar to what is used in black tire covers.

I will show the meter readings for each "shield".
Full Sun gives a reading of 9 which is considered "HIGH"

 while in full shade the reading in zero.

Under the white cover the reading is zero

 and even under the black cover the reading is zero

.

  but the screen only reduced the UVI to level 5

I interpret these results to indicate that anything that is not in direct sun or that shields all direct sunlight will provide adequate protection from UV damage for tires.

I would not be worried about reflected light going under the RV to the back side of the tires as this is full shade. After all, tires are designed to be outdoors and we are not trying to protect tires for 20 years but only to get past a normal vehicle usage of 4 to 5 years to the 8 to 10 year range for many RVs. I would not consider open mesh as used in some "tire covers" complete protection but it is probably better than nothing.

NOTE I did not address the effects of heat on tires in this post. I did cover in THIS post and that clearly shows that white covers are the ones to use if you want to keep your tires cooler so they age more slowly.

BOTTOM LINE
If you want to protect your tires to give you the longest life possible you need to cover them with white solid covers such as cloth backed vinyl being a most reasonable option.