Got this question and thought I would share my answer
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.
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
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 "underloaded" 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.
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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