RE: Sumitoma tires
I've been running two Sumitomo tires, 8 x 19.5, on my Coachmen for about 10,000 miles. I had Equal put in them when new and ran them on the front for a while. They bounced a bit over 65. I put them on the rear and put Hercules on the front. The Hercs are a bit smoother, also with Equal. Both Herc and Sumitomo were smoother than Goodyear and a good bit cheaper.
$1700 seems high for six tires. I believe I paid about $200 each for mine. The Hercules were cheaper than that.