1970 dodge dart front disc brake conversion

There's nothing comparable about those two situations. When you change to radials you've already thrown the stock suspension geometry out the window, your alignment MUST change from the factory specs. When you lower the car, you've changed the geometry again. If at that point you add modern compound tires that have significantly better grip, you guessed it, you need to alter the geometry. Maybe the FMJ spindles aren't ideal for a car at stock ride height with bias ply's (although thats still arguable). But technology changes. Almost no one runs bias plys, and very few run at stock ride height. That's why I posted the article. The authors very clearly list the conditions they tested, and posted all of their geometry numbers plain as day. The physics is right there. I don't care who said what when, the data doesn't lie, the change in geometry is negligible to better. I run FMJ spindles on my Duster and my Challenger and have logged tens of thousands of miles between them with none of the ball joint or alignment problems claimed by Ehrenberg and apparently others. It's not about out smarting the engineers, it's about thinking like an engineer and matching the geometry to the new components so everything functions properly. That's hot rodding.

When you put the wrong size tire on a rim like you suggested in the other thread you've just put the wrong size tire on a rim. It's not comparable at all. If anything, the fact that you're putting an oversize radial on a SBP rim designed for a bias ply makes the situation even WORSE, because radials load the rim lip more than bias ply's do to begin with, even when properly sized.