Every truck gets washed after every storm. Now they don't get washed as soon as we are done plowing, it is more like the next day is when we wash them. I have to bays in the shop with trench drains, and drive through doors. We can fit 4 1 ton dump or rack bodies in at a time, or two big trucks.
All we use are regualar watter pressure. Then we use some soap, and rinse them off. In the winter things get washed about once a week, because it takes a few days for all the grime to dry up on the roads.
Geoff