One investment we knew we had to make was a tire monitoring system. We knew we really had to pay attention to the trailer tires, you know, those China bombs! But, really, a closer eye on the tires was a definite for us. I ordered this off of amazon, you can find it here:
We have been super pleased with the unit so far. Kevin set it all up and I attach it to the windshield of the truck (with a hundred other monitors and cameras!). We can clearly see the temp and pressure of each tire. We got the 8 tire unit because, well, we have 8 tires :-)
Our truck came with the TPMS, but we wanted to see the temps of each tire as well. This little unit works great and it lasts for days. Now, in the mornings before we leave we turn on the unit in the truck and let it cycle through all of the tires and we can see the pressure before we even leave! It sure has made things easier.