I agree on the Firestone 8.75 R 16.5 tires. I put them on my clipper and they run great. I know some folks have switched to the 16s, but my local tire shops will order the 16.5 and match online prices, so I figure it's not worth switching at this point.
They were also the very first purchase I made when I bought my clipper. I had read about a blowout with another clipper - the undercarriage, tanks, pipes, wires, etc. were all damaged. Stuck in the middle of a trip with the RV in a shop costing a ton.
1975 American Clipper RV with Dodge 360 (photo in profile)
1998 American Clipper Fold n Roll Folding Trailer
Both born in Morgan Hill, CA to Irv Perch (Daddy of the Aristocrat trailers)