A couple of things to worry about if you go up an inch in wheel diameter. Of course you must have new wheels, so just be sure the new wheels meet the width and weight-carrying capacity specs for the new tires.
I'm a big fan of increasing the weight capacity of most stock RV trailer tires. Many have barely enough weight capacity to meet the combined GAWR of your trailer. Keystone is one of the culprits that shrimped on tire weight capacity. My 2000 Keystone Sprinter blew out two stock tires on the first long trip. They were ST205/75R15C. I replaced them with ST225/75R15D, and that was the end of my trailer tire problems. The ST225s required 6" wide rims, so even though the old tires were also 15", the old rims were only 5.5" wide.
The bigger tires reduced the clearance in my wheel wells to just barely. So I had rubbing between the top of the tire and the underside of the wheel well when I hit a bigger than normal bump. So I tried to avoid chug holes and big bumps. I drug that trailer about 100,000 miles over 10 years, without any more tire problems and without any real damage to the wheel wells.
My newer TT has ST205/75R14C tires with 1820 pounds weight capacity per tire. The TT's GAWR is 1,400 pounds per tire, so I have over 20% excess tire weight capacity. I like 20%or more excess tire weight capacity, so I'll probably not go to the available ST205/75R14D when it's time for trailer tire replacement. However, those tires have 2150 pounds weight capacity per tire @65 PSI, and they are the same width and height as the stock tires. So if your trailer has ST205/75R14C tires, consider upgrading to load range D instead of to a bigger tire.
I'm a Maxxis trailer tire fan, and they make ST205/75R14D tires. So consider those when you upgrade your tires.
M8008 ST Radial