There are a lot of variables there, but in general a 'high-powered pressure
washer' could 'damage and weaken' just about anything. Like many things it's
all in how you use it.
Put another way, with my standard setup you could spray your arm, say (not
recommended, btw), from 10-12 inches away without harm, but at 2 inches the
same setup could cut your fingers off.
In other configurations I'm sure I could easily shred a tire; I've seen
demonstrations of people damaging/cutting concrete and even sheet metal.
If the concern was that the pressure washer could cause undetected damage
during what might be seen as normal use, I could see that happening as well,
again depending on the user mostly.
I routinely run my machine at temps of 180 F (though generally not when
cleaning a vehicle) ; does anybody know if exposure to that kind of heat for
short periods can harm the structure/materials of a tire?

Cya,
Robert

On 1/14/08, Vdub Guy <fonman4277@comcast.net> wrote:
>
> I<if you have a power washer, nail them with that.
> If not take a soft, long bristle brush, and lightly go over the caps.>
>
> I read somewhere the other day that the really high powered pressure
> washers can damage and weaken the sidewalls of tires. Think it was in
> Popular Mechanics....      jeff
>