If your spare uses the same brand/model rim check it for a PSI rating....., but I would think with an aluminum rim an additional 15psi would be ok, but confirming would be wise.
Sometimes manufactures stamp the ratings on the "inside" of the rim where removing the tire is required.
Give Jayco a call (have your VIN handy), they should have this data.
Bob
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2016 GM 2500HD 6.0L/4.10
2018 Jay Flight 24RBS
2002 GM 2500HD 6.0L/4:10 (retired)
2005 Jayco Eagle 278FBS (retired)
1999 Jayco Eagle 246FB (retired)
Reese HP Dual Cam (Strait-Line)