The 444-544 hub lugs are five on 4-1/2 inch diam. circle, same as most Ford Chrysler, and AMC rwd cars of ~1950 and later, and Ford Ranger trucks. The metric equivalent in mm (multiply 4.5 by 25.4) is used by many Japanese and other makes, including I think, Toyota trucks.

The standard 544 rims, made for stiff-walled bias-ply tires, lack the groove that helps hold the tire bead in place in case of deflation while rolling, and are 4 inch width (measured as usual between the flanges that the tire sees; add 1/2 inch each side for total width) This width is awfully narrow for modern, low profile tires of adequate capacity. Look up rim width specs in www.tirerack.com for modern-sized tires under consideration. Old catalogs I have give a rim width range of 4inch to 5.5in. for 165-15 tires, which are esentially 80-series profile. Stockton Wheel and others can add new, wider steel rims to your original center sections, to ordered backspacing; they're online.

See John Mc's posting, and his follow-up posting, here:
http://www.swedishclassics.com/cgi-bin/swedish/wwwboard/messages/20961.html

The 444 was supplied in its early years with 16-inch wheels even narrower than 4 inch, which may explain the oddly tight suspension clearance to 15x4 wheels.