It is really high. Do you have the Newmar recommendation (135 PSI) in writing? Look at it this way if you are at GAWR for each of your axles the Michelin PSI recommendation is:
Drive axle is 20K lbs GAWR. This means 85 PSI
Tag is 10K lbs GAWR. This means 85 PSI
Steer is 17K lbs GAWR. This means 125 PSI
I doubt you are at GAWR. It is possible, but I doubt it. Consider having the coach four corner weighed after you load it for travel. Newmar should have done this and the weight should be on one of the stickers inside one of the cupboard doors. That weight is with a full fuel tank but nothing else. Anything you add (like fresh water, propane, your stuff and people must be taken into consideration).
The minimum PSI Michelin recommends for your tires regardless of weight is 85 PSI. On the sidewall of the tire, there should be a maximum PSI stamped on the tire. For your tires this is:
9090 lbs = 130 PSI for single
8270 lbs = 130 PSI for dual
This is the weight on each tire.
Go to the Michelin RV tire chart at Michelin North America RV Load & Inflation Tables
and download the inflation table.