^^^ Ford E350 from CHASSIS Year 1984 and up will accept late model wheels. I was corresponding with Grillmeister back in those days and saw a pic of the new wheels. He said they just mounted right up. He called his RV "1984" and so was his chassis. Ours was also "1984" but chassis was 1983.
Barry's Tire Tech will show that if original is 8.75/16.5, then the LT225/75R16E is very close to an exact replacement. So long as OFFSET is OK, and if the tires/rimes are OEM, it should be OK. Barry's calls for 10.2" of which half would be 5.1" but some sources call it 5.15"
But this is an older (1983 and prior) E350 and has the lug-centered coined wheels.