Cascade Crew

Midnight Sun · Posted: Mon Jul 05, 2004 11:58 pm Post subject: Dually's..?

This something I see everyday and never think about, but now I am really curious about.

Most dually trucks and almost every semi I see have front wheels that appear to stick out, and I am trying to figure out why. Are they stronger? Do they assume that if you are buying a dually you will just need a stronger front wheel as well?

Or does it have something to do with tire rotation or tire wear and tear?

Just curious... and I bet someone here knows why.

Demon · Posted: Tue Jul 06, 2004 3:11 pm Post subject:

non-4wd and duallies have a different bolt pattern so they do it to make it uniform

:pulledoutofass:

rjmcgee · The Hammer Joined: 08 Jan 2004 Posts: 2328

Picture how the front wheel on a semi are convex and the backs are concave. The inside wheel on the back duals is mounted convex like the front and the outside is mounted concave. This gives the offset needed to allow the wheels to be mounted together and not need any kind of spacer while using wheels that are the same regardless of front or rear.

The inside wheel on a dual set up are held on with lugnuts that are called thimbles. They have a taper on the end like normal but are also threaded on the outside. When you put the inside wheel on and all 10 thimbles and rattle them on tight then you have the studs for the outside wheel and you put on your normal lugnuts on the thimbles. Plus with trucks when you go to change a tire always look at the end of the thimble to see if there is an L or R. Trucks still use left hand threads on one side and right hand threads on the other side.

BTW, Aaron, you should put your answer back where you found it. Razz

Demon · Posted: Tue Jul 06, 2004 3:42 pm Post subject:

rjmcgee · The Hammer Joined: 08 Jan 2004 Posts: 2328

I editted it to add some more. Smile

Flyte risk · Member Joined: 21 Jan 2004 Posts: 55 Location: Aloha OR

Only half correct there Rod-meister. The old style stud piloted wheels mount like that using the nut/thimble approach. The new hub piloted wheels use a single captive washer style nut. You just toss both wheels on the studs and hammer all 10 nuts on then call it good.

Just to point out the obvious that most everyone overlooks. If you do the math using a rim meant for a dual application as a single it applies more load to the bearings through leverage because of the offset. Just one more reason dually front ends seem to be heavier built, they need it.