We had a 2001 Sprinter 25RK fifth wheel. Almost perfect for us two old folks. We drug that RV all over the USA more than once over 10 years. After 10 years, we sorta gave it to a daughter who is living in it.
Our Sprinter was upgraded with gel siding, day/night shades, 15k AC. Like all RV trailers, the factory tires were barely adequate for the wet and loaded weight of the trailer, not heavy duty enough for long-distance traveling. So we replaced the ST205/75R15C tires and 5" wide wheels with ST225/75R15D tires and 6" wide wheels. After that, we had no more trailer tire problems.
But barely-adequate tires is not just a Keystone problem. Every RV trailer I've looked at had barely-adequate tires - including my new Skyline Nomad Joey 196s TT. So if you plan on long-distance towing, plan on upgrading the tires before you head out. And the 225/75R15 tires require 6" wide wheels, so you'll probably need to replace the wheels too. A good source for inexpensive trailer wheels is Southwest Wheel. For example:
The 318FLS has a GVWR over 11,000 pounds, and a wet and loaded hitch weight of about 1,300 pounds. Too much for a half-ton pickup or full-size SUV. So I hope you have at least a three-quarter-ton pickup to tow it with.