Back spacing
 

What is the optimum back spacing for widest tire for a 63 Catalina? 15"X8"

Great question. I think that a 5 inch backspacing is the most you can do. I'm getting ready to order some wheels for my '63 Catalina Safari.

Rob...

Here are a couple old discussions about backspace for a '63:
http://forums.maxperformanceinc.com/...d.php?t=460244
http://forums.maxperformanceinc.com/...d.php?t=540067

63 or 61 - may not be much difference. My 61 had 15x7 with about 4 5/16 backspace and 215/70R15 tires. I thought it had the tire to close to the outside of the fender and wanted to get more space. Couldn't seem to find a wheel listing that got a little more backspace even though I thought I could tolerate maybe and inch more backspace than the 15x7s. I have an additional problem in that if I did find a wheel with more backspace I would have a problem with my front tie rod ends. (I don't have stock Pontiac steering arms so it makes a difference if I want the same size wheel front and back.)
Anyway, I would guess that you may get by with maybe a 15x8 if it has about 5 1/4 backspace. But find a dealer who is willing to try several combinations on the car before you lay out the money. Mount them up and put on both front and back and check for problems. I ended up with 15x6 Torque Thrust and still 215/70R15 tires to gain a little more tire to rear fender clearance.

...the '61/'62 rear inner wheel house is narrower than the '63/'64...those guys (the new car types with the '63/'64 cars) have all the luck.

I called these guys and they will make me a 5 hole style Chevy stock truck wheel 15X8 with 5" back spacing for around $90 each. The 65 dog dish caps fit them. http://diamondracingwheels.com/contact.html

If you don't mind let me know what you think of their work. I am contemplating using them for a set of wheels.

They do great work. Actually make NASCAR wheels. They're on 6th or so & Layton.