RV Tire Safety
with RV tire expert Roger Marble
I was recently reading a forum where the owners of one specific brand of trailers were complaining about the $21 the RV company wanted to charge for a spare tire cover.
I have previously covered in detail the advantages of and “why” we should be storing our tires inside or under our RV or under light-colored covers. It is the HEAT that kills tires, and the aging effect on tires is exponential (doubles for each 18° F). With such an increase in temperature, you could end up with a tire failure with ZERO miles, as seen in this example.
I pointed out, with temperature data, in the above-referenced blog post, why white tire covers are good and much better than black covers.
This shot (left) shows what can happen with a black cover that effectively places the spare in an “oven” where cooling air can’t offset any of the sun’s heat.
You will note that in both the above examples the top side of the tire (location with most direct sun heating) is the location of the failure.
These folks do it right (see right).
I know of no tire shine or protectant spray that provides protection from heat.
Read more from Roger Marble on his blog at RVtiresafety.net.
I’ve used both black and white tire covers, and have measured the difference in tire temperatures which in both cases was far lower than while driving. The temperature difference between white and black was negligible.
Interesting. When I did my controlled test http://www.rvtiresafety.net/2011/06/tire-covers-do-they-do-any-good.html it measured over 36°F hotter with no white cover. This translates to aging (heat degradation rate) being 4 times faster with no cover than the white cover. In my simulated Black Cover test, the temperature of the cover was the same as the temperature of an uncovered tire with an aging rate of 4 times the rate if covered. Yes, these temps are lower than when driving but you need to remember that rubber degradation is cumulative. Just being cooler does not repair the damage done. Look at the two failures at zero miles in this post, can you explain how the heat was not the cause?
Mr. Marble, yes: UV. I’ve confirmed with both Michelin and Goodyear techs that UV is the “hidden” tire killer. If sun heat so damages a stationary tire, why not make them white? A search will confirm black does a better job of handling UV than white. I confirmed this with a manufacturers rep who told me their black roof-mounted unit covers are lasting longer than the white ones they formerly used. Some interesting proof: we recently moved, and while packing our yard tools, I found a plastic trowel that had been lost, and laid in the sun for 7 years. The trowel portion is black, with a white cap of the same material. The black trowel piece is like new but the white cap is very deteriorated?
The issue is not whether the white or black tire cover lasts, but whether the tire does.
Yes, some additional points in favor of black covers: white only works with direct sunlight (it does not reflect heat – only sunlight), while damaging UV rays can be reflected. Also, up to 80% of damaging rays come through on cloudy days, and cause damage during colder/winter days, when heat is a total non-factor. That’s why, over time, UV has much more of a deteriorating affect on tires than heat alone.