It depends on what size tires it has on it.  The original tires are on 17" wheels and those tires need to be special ordered from from Universal Tire or Coker Tire.  Those utilize a split ring wheel and you will need to go to a truck tire place to get them serviced.  They are a tube type tire and wheel.

https://www.universaltire.com/750-17-sta-super-transport.html 

Coker Tire:

http://www.cokertire.com/750-17-tornel-lt-truck-hwy-10-ply.html 

They have been available from Michelin as a radial tire as well but recent reports say that size is no longer available from them. The above tires are bias ply.

If you have 19.5" wheels, they are widely available and I would also go to a truck tire place to have them serviced.  Some coaches were converted to 22.5" wheels to achieve a taller gear ratio and those tires are also widely available at truck tire places.

I have looked at the pictures of your new coach and it has the 19.5 Alcoa aluminum wheels.  Those are the desired wheel. 

Nice looking coach.  You got a good buy.

It is common for these coaches to have some steering issues as they age.  It is NOT common for the problem to be the steering box.  If it is the steering box, those can be rebuilt or rebuilt units secured.

The much more common source of steering issues are all of the joints between the steering wheel and wheels.  There is the front to deal with and there is the back wheels to deal with as well.  Both have to be up to snuff to have a good handling coach, and many coaches are good handling.

Most front end shops have no idea how to correct issues in the front.  They just start replacing things on your ticket.  The first thing is to do a proper evaluation of all of the steering components.

The tie rod ends are easy to check, but most shops do not understand the need to or how to check the pitman arm mechanism that attaches to the frame and the rag/flex joint within the steering column.  These coaches are rear end heavy so all steering components need to be properly maintained and replaced/repaired as necessary.

To prevent rear end wag (which causes steering issues) the rear wheels need to be properly aligned as well with the coach properly leveled (the unit has independent, swing arm rear suspension).  Many coaches have had Timbren rubber bushings added to the rear suspension to help control rear end movement.  They greatly aid in rear end stablization as the rear torsion bars have aged.

I would do nothing until I had a chance to drive it and get it to a place where I could take my time doing a proper evaluation of any problems before having shops do any work to it.  The stories are many of shops saying "xxxx is what it needs" and doing the work and it not changing anything.

They are great handling and driving coaches when properly set up.  At the rally this weekend in Northern CA we are having 10-11 coaches coming from CA, OR, and MO.  They would not be coming if they had major steering issues.  Analyze multiple times, fix once!

If you haven't already, go to this site for and review the appropriate Owners, Parts and Service manuals: http://www.fmcmotorcoach.com/index.html .