I decided to install 15" tires and rims and bought a set of Sendel T02-56545T rims which take 0.453" stems and had the sensors from the Dill 1504 kit installed along with the new Towmax STR tires.
Dill sensors were installed by the Firestone dealer that I bought the Towmax STR's from and the system works well but I do have to use the remote antenna that came with the Dill 1504 kit. Takes a while for the display to sync with the tires - as much as 5 - 10 minutes - but once it does it works well. Setup is a 1998 25 ft Safari hitched to a 2010 GMC 1500
Only drawback to the Dill system is the display. You simply cannot read it during the day if it's mounted on your windshield. Display is too dim and washes out in sunlight.