I have 15" Fuchs (7" front and 8" rear, I believe) on my '84 with 215/60s on the front and 225/60s on the back. The big problem with tires for these wheels is the selection. When I was looking for new tires last year it was quite difficult to find a single tire design that had both of these sizes in their range. I ened up getting some Dunlop Sport A2s which I think were the only ones I could find to meet the criteria. I'm not very happy with the A2s as the sidewall flexes way too much for my liking (compared to my previous Michelin MXXwhatevers). I would like a higher performance tire (the A2s are classed a 'All Season High Performance') but still the selection is very small.
I'm thinking about finding some 16" wheels to replace them as I'd like to get some Yoko ES100s. I wouldn't mind some wider wheels than 7", though. Were the PDs that came on Turbos all 7" as well, or were they 8" on the rear?
I would think that as long as the PDs were from an 86 or earlier they will have the correct offset. Anything later than that will need spacers to fit properly. Dunno how you can tell just by looking at them, though.
My experience has been that going to a larger-diameter wheel with lower-profile tires will give a better cornering feel just because of the lower, stiffer sidewall (all else being equal). The difference is more than quite noticable. The only drawback that I can think of is the slightly greater mass of the larger wheel. That might be offset, though, by less mass of the tire (theoretically speaking, no idea for sure).
I say go for it
