What's the problem?? Are people flashing you all the time on the road? If they are, you may have the lights aimed too high, mounted too high on the truck, or a combination of both. If they really are a fog beam pattern light, and not a driving pattern light, then they should be mounted low and aimed low to illuminate the road in front of the truck, not down the road.
If all that fails, you might be able to find a Pilot 35W bulbs to replace the 55W.
Give us some more info to make sure we are addressing the right problem.