What material to use on an 18 wheeler trailer?

The best cast vinyl you can get.

 

I can't see that situation turning out well with vinyl. If he's washing with harsh chemicals tell him to have it painted. Otherwise it will end up being a never ending spiral of fixing failed material.

 

I have done septic trucks, asphalt tankers, concrete trucks....all with cast vinyl. I know that aren't washing them with baby shampoo and washcloths and most have held up well. Of course I also always give the standard warning about pressure washing and harsh chemicals along with the "no guarantee" line.

 

Someone on here had recommended to me the 3M 7125 for some police cars I was doing. The previous decals (from another company) peeled off twice, not sure if it was the vinyl or installation error. Anyway, I used this vinyl and no issues. Something to look into...
From the bulletin: Resists mild alkalis, mild acids, and salt. Excellent resistance to water (does not include immersion)
http://multimedia.3m.com/mws/media/...-electrocuttm-graphic-film-series-7125-pb.pdf

 

just black? not the shiniest material but what about 3M economy controltac vinyl??( good god.. they should better name this product so everyone could find it easier...(

Basically it's a 1080 vinyl but calendered! only comes in gloss and matte black. 60 inch width. It has air release. Calendered so it won't conform as good but we have done flat trailers and it worked out great. Not as shiny as cast 2080!
You could also try to laminate it for extra protection. You might be able to find it if you search for 3M VC19161

fellers shows nothing if you search for that

 

I use ORAFOL 970RA Wrapping Cast. It works well, Comes in gloss or flat black.

 

We've done this before for small trailers. We used the 3m economy (controltac). It sounds like the guy wants an inexpensive quick fix.
Flat surface, it will work fine.