Firstly, I do have 225-17's on my current ride, a VW Sportswagon, and, of course, I do think the fat tires give a superior hold on the ground. But I have been thinking about whether the skinny 195-16's might be better than the 205-17's on the 124 Spider. The lightness of the car seems like a special feature, not to be squandered unnecessarily. From the bicycling I learned that spinning weight is "heavier" than the not spinning weight. I cannot hope to begin trying to do the math on it but we'd be talking about four spinning wheels plus the spare. If the real effect added up more than one hundred pounds, I think that would be worth consideration.