Nobody?

You sure got that word stuck in your head.

You'd also be wrong about the tire diameters as well. Try fitting taller than 24" tires on an early A body without sheet metal mods.

https://www.forabodiesonly.com/mopar/threads/help-with-64-dart-gt-tire-size.96214/

A bunch of people running 205/70-14's on Early A's (okay didn't look up a 60 valiant or anything) which are 25.4" tall. Looks pretty easy. Of course you can do what you want it doesn't really matter to me.

In any case, you will not find many people installing tires that small, and definitely not on a 67+A/B/E/F/M/J, likely see a tire 25"+ in which case its quite easy to upsize your wheels and have lots of options (really a lot in the 25.6-26.3" range)

Again, my recommendation of the stock brakes in that case and hydroboost stands if you want to stay with them. The hydroboost alone with increase the performance of any system, especially if you're not able to lock the front wheels easily (more pressure available). OP was clearly talking about brakes for 15" + wheels anyway

Why do you do this?

Do you consider anything with a 70% aspect ratio a performance tire?

No. Anyone running a 205/70Rwhatever is not interested in handling, period. Why use them as an example? This is the handling not the resto forum.

I have 245/40R17's (24.7") going and some sheet metal mods and attention to backspacing is needed. Anything more than that and you will be cutting metal out. Remember we are talking about over all tire height now, not rim diameter.

Years ago I ran 245/60r14's in the back of my 72 Swinger and it would rub the inner fender in hard turns. That was with about a finger's width of clearance between the leaf and the sidewall and about the same between the rolled fender lip and the sidewall. I probably could have gone taller, but it would have just hit the inner fender sooner. The sidewall would also rub the side of the leaf in hard cornering, which I put down to sidewall flex due to the high aspect ratio, which a 70 aspect would just aggravate. What that Swinger needed was a shorter sidewall height and more spring rate, already had a rear bar in it.

Kind of wondering the same??? I'm advocating larger wheels for shorter sidewalls

I don't consider that to be a performance, but my point was people in a lot of cases run taller tires, so yes they fit. I also don't really consider running 14" anything to be optimal for handling/braking, etc as I've stated.

You aren't even using a sub 24" tire so I really don't understand why you had to get difficult about "nobody" - basically making my point for me - and yes this is in the context of the handling forum. I think in general we agree that large sidewalls flex a lot, but in the context about handling and increasing braking performance, put some bigger wheels on it - then you can upgrade everything else too.

I have a 1970 Duster with 275-35-18's which are 25.6" tall and by pushing the fender brace out, using the correct backspacing wheels, a minor grind on the Plymouth only fender brace tab, and a pan head bolt and they turn excellent. The back has the MP offset shackle kit, B-body 8 3/4 and no other mods.