More details on the 19.5" tubeless dual wheel swap.
Comparison of the new 8R19.5 tire and wheel beside the original 18" wheels and tires.
PICTURE Rough measurement shows almost 2" taller.
PICTURE Checking fit of inside dual and the brake drum, it is an EXTREMELY tight fit. About 1/16" clearance between corner of drum and wheel center.
PICTUREIf it were any closer we'd have problems. These 19.5" wheels have a more or less spherical dish to the center. I've had some similar 19.5" 8 lug wheels that had a more conical (straight/angled and not so curved) dish to the center, those different wheels may or may not fit (I don't have one anymore to test).
Here's an overall picture of testing that first wheel and checking clearance.
PICTURE**Next issue is stud holes and the wheel studs.
PICTURE The original wheel studs are 1/2" and the wheels will accommodate 9/16" studs. This leaves some room around the studs but luckily enough the wheels are what is called "hub centered" in that they fit snug at the center bore and the hub, so a snug fit on the studs (and tapered seat lugnuts) is not a necessity for centering the wheel.
Had a friend hold the brake and I rotated the wheels to take out the slack such that when driving forward the studs are already contacting the appropriate side of the lug holes, then torque the lugnuts.
Picture of wheels installed.
PICTURE Don't forget the clamp plates and be sure they are installed dimple side out, or if using more modern ones countersink/bevel side out to fit the appropriate lugnut. A black and red clamp plate is visible in the picture linked above with ** after it.
Next, driving report and more/better pictures of the truck,
Grigg
