GMC SceniCruiser Bus Model PD-4501

[Johnybotto]

Here are a couple of pics. It looks like chains are attached around the axels with a few more attached to the corners of the tractors. And in some cases tire chalks are used. I hope these help,
John

[Paragon]

Many thanks! I can make use of these. I like the stacked tires as well.

[Chacal]

You'll need chain binders too.
Here's a detail picture.







No idea why this tractor is wearing a red tie. Must be an executive tractor.