My Minuet shares most specifications with your Caravelle. I have been running Goodyear Marathon ST tires in the following size:
While load range C was acceptable for the coach, I elected to go with load range D for a wider margin of excess capacity. I know that many have had problems with the Marathons, but I have had nothing other than good luck with mine since 1981. My only deviation from Marathons for my coaches was in 2008 when I couldn't source a set and had to settle for Carlisle ST tires in the same size and rating -- and thus far, I have been satisfied with their performance on my tandem axle Overlander.
My first tow on both of my coaches was on bias ply trailer tires -- and in my opinion, the radials offer superior control and performance.
Good luck with your investigation.
Kevin D. Allen
WBCCI (Lifetime Member)/VAC/Free Wheelers #6359
1964 Overlander International/1999 GMC K2500 Suburban (7400 VORTEC/4.11 Differentials)
1978 Argosy Minuet 6.0 Metre/1975 Cadillac Eldorado Convertible (8.2 Liter V8/2.70 Final Drive)