I would also go with the 15" just because there are many more drag tire choices for 15" wheels.
The 14" Quick Time Pro (26/9.5/14) would give you an extra inch of rubber to cushion the shock of launch compared to the 26/9.5/15's, but I would still stick with the 15" for tire availability.
The rims I want are available in both so that is not the problem. I have a matching pair of 14" front rims already and was just tossing around as to whether there was a theoretical performance advantage in one or the other.
I'll restate my question differently:
Will an equal height/width DOT bias drag tire work better on a 14" or a 15" rim? (What affect does the additional side wall height play with drag type tires, given that everything else is equal?)
Good info with a follow up--Is the cushion a good thing or a bad thing for overall traction with a 4 speed? Will one lessen my ET more than the other (everything else being the same?)
Sidewall flex (or wrinkle) greatly helps a hard leaving stick car. Given the 2 tires I mentioned, the 14 inch will have slightly more sidewall flex because it has one inch of extra rubber in the diameter. Would it be enough to tell a difference in ET? Who knows? You would have to do a back to back test to see for sure.
I have heard good things about the Quick Time Pro's. I don't think you can go wrong with either size. But in the future if you want to change tires there is definitely a greater array of tires in the 15" size.
If your suspension is set up correctly, these tires should let you see the capability of your car.
I went with more of a "street" type tire in my automatic car choosing the 235/60/15 MT Drag Radials. I have seen a Fox body Mustang lift the tires and run 11's with them so I will not blame my tires if I can't hook now
The slick type tire will be a little easier on your drivetrain than the drag radial..... Really 14 to 15" you will have a better tire selection with the more common 15". For your (and my) power needs the 15" will take care of everything you can throw at it....