What chassis ?

Call Monaco with the last six numbers of your vin or look in front of a front tire and see if there is a airbag there. Pretty sure you will find one there and behind the tire making it a RR8R. Same on the rear axle but easier to see them on the front.

What's an rr8r

I'll go look now

It does .... Both in front, and behind the front and rear tires

A 99 Monaco will have a roadmaster chassis..exclusive to Monaco. The RR8R means you have 8 airbags. The RR4R chassis had trailing arm issues.....Dennis

The RR8R chassis is one of the best handling ones built although some feels it rides too stiff. It shines on curvy roads without leaning or losing control without the use of sway bars. In later years ping tanks were added to soften the ride of the front axle. Weighing your rig and adjusting the tire pressures is especially important on the front axle.
What size tires do you have and how old are they.

Yea.... I need new tires (age) 275-70-R22.5 He said he never replaced any tires, but the front tires I believe are 08 date code.

The funny thing was the previous owner all he kept talking about is how good it handled and it was one of the best chassis. So I asked him which chassis it was and he was like .. ahhh its in all the paperwork.

OP, you need to call Monaco ((877) 466-6226 + last six of your vin) and check on a change in tire size to something bigger than the OEM 275/70/22.5. You also need to weigh your rig loaded for travel with full fuel and at least 1/2 water before replacing your tires to confirm if you need tires with more load rating.
I seem to remember that a 295/80/22.5 is what was recommended but this was a long time ago. There is a lot of info hidden in the SEARCH BOX, especially the advance search that will let you search for things from more than the last year. Try RR8R.
PS: Welcome to the forums.

You done good. The Monaco Roadmaster 8 outboard air bag chassis in one of the best in the industry, The best if you delete the foretravels and other million dollar coaches.