68SS - I just left my old wheels and tires bolted on and measured off of those to the outer fender lip and to the inner wheel well. Then I measured the backspacing of the old wheel and made a drawing, to scale, of the old setup. This helped me figure out what backspacing my new 15X10 wheels should have. In my case it turned out that 15X10's with 5" backspacing (zero offset) would center the wheel and tire between the outer and inner sheetmetal. The other day I measured my BFG radial TA 295/50-15 (on 15X10 rim) and found they were 12-5/8" (320mm+) out to out of sidewall . That would explain why It seems like I have a little less clearance than I thought I should have as the tires are about an inch wider than I thought they'd be. Just something else to thing about.
Like I was saying before also, I've seen a couple of other posts where guys were selecting tires and comparing a 275/60/15 from two different tire makers. For example, the overall width of a pair of Goodyears side by side a pair of Firehawk Indy 500's showed the Goodyear sidewalls stuck out a bit more. Maybe that could also explain some of the clearance miscalculations? By the way, I measured the tread width on my cheapie Remington 245 tires last night and they're 8-inch tread width. They sure look wide from the back though and I can't imagine having that wide of a tire up front!
I'm also getting an early start on shopping for wheels. I'm down to either Convo Pros, Weld Prostars, or centerline Telstars like you've got. Satelliteman, any chance you could post a side view of your car with the Telstars so I can see what they look like front and back on your car? Anyone else out there have a 68-69 plymouth B body out there with Weld Prostars or Convo Pros on them? I think I'm leaning toward the Prostars but I heard the Telstars shine up better. For the longest time I always wanted a '66 Nova with Convo Pros, but then when I bought this 68 plymouth and saw a '70 plymouth with Convos on it, they didn't look as good to me on this car as they did on the Nova.
I promise I'll post pics soon. I got the car back, but have been working on some engine issues and it's parked where I can't get a good shot.
--68 Sport Satellite