Good Morning, The 18's are available through Coker and the antique tire route. I have mixed emotion and have to believe the date codes you will get off Coker will be "older" as this is such an unpopular tire size.
I imagine there are companies out there to re-tread the 18's but I have found sidewall quality to be the limiting factor. You'll need a good "starter set".
I went the route of 19.5's and have not looked back. There are many manufacturers out there with different levels of quality - mine are Chinese.......
I can't opine on "ride quality" as I hover at 65 MPH top speed with the 4:11 rear conversion only not to strain my engine though I am sure it could handle it all day long (1962 full pressure 261). I think there are some pictures of my "build" through my signature -
Joe
