Assuming I have to put my spare on could I get away with the smaller tire on the spare or will that cause issues? I have Dexter EQ-flex suspension so I would imagine the suspension would not love it, but should work right?
The 15" will work fine as a spare tire that probably never see the ground.
Just about every trailer with 15" ST tires I've owned (rv and non rv) I always dump the STs and go with a 16" LT.
My current '97 11200 lb 5er came with 15" ST tires. I sold them to a guy with a lawn service trailer and went with a LT215/85-16 E at 2680 lbs capacity.
Just be aware using a different diameter tire or a tire with a different tread pattern or tire width on the same axle can have different braking performances on hard braking events.
"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers
'03 2500 QC Dodge/Cummins HO 3.73 6 speed manual Jacobs Westach
'97 Park Avanue 28' 5er 11200 two slides