Hi Willy1962,
I'll let you into a little secret of mine...If you place the Mack Mod above the Kenworths and other trucks in the Mod Manager you can put the Mack wheels onto the Kenworths.
What you need to do in order for it to work is first select the tyre on the Kenworth in the Upgrades Shop/Showroom and choose the "RTA Continental" tyres from the top of the list. When you do this the existing wheel on the truck will disappear but if you select the wheel hookup point now you will have the options to put the Mack wheels, hub-covers and wheel nuts onto the Kenworths (and other trucks)
Also I found that the T609 needs to be below the trucks you want to put the Mack wheels onto in the Mod Manager load order, otherwise the centre hubs of the Mack wheels will be replaced by the centre hub of the T609, which can be handy if you want to change things up a bit more.
I have put a couple of pics below of some skins that I've been working on, and you can see what I mean. The Mack wheels just finish the look off well I think.
Now that I have let the secret out, I hope they don't change anything to "fix" this little trick, as the Mack wheels are my favourite on my trucks
Hope this helps you out, happy tucking
Geronimo...
Added after 8 minutes 19 seconds:Edit: That was meant to say "happy trucking"