Slick size

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J

jimmyjeep

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Ok I have the start of a game plan. I have a built engine, 440+.020, 10.5 compression, 906 heads with work, and a 727 tranny. Lets say conservatively 450 hp. I have the 66 b-cuda to put it in. I have decided to go with the ford 9 because of its price and availability. To shorten it , I need to have my tire and wheel combo picked out.(Dyno straightened me out on that).I know I don't want to run any more than 5500-6000 rpms. I need to figure out what tire size to use. How do you do that? 6", 8", 10" slick? Whats the formula. Thanks.
 
It's the diameter of the tire you use in the equation, the width means nothing for the rpm calculation. I have a 28" tire in the stock wheel tubs in my car and it is to tight for a street driver. If you use a 26" tire and say you went thru the lights at 110mph and you wanted to limit your rpm to 6000 you would run a 3.91 gear. With the same tire size but only 100mph thru the lights you could get away with a 4.30 gear and stay below the 6000rpm.

Here is a calculator
http://www.moparts.com/Tech/tech/index.html


Chuck
 
You want to run the tallest tire you can fit, then the widest for that height. Taller tires give a longer contact patch than a shorter tire of the same widht. But, knowing 66s a little, I'd think you're stuck with a max diameter of 26 if you're lucky. The wheelwells are just shaped wrong for really big tires. Then you gear and convertor it to get the engine in it's power band and keep it there. With a 25 or 26" tire and 5500 rpm, you are looking at 3.91s or 3.73s...
 
I've a '65 Dart. Should be the same opening. I got a 28" cheater in comfortably. Dosen't hit during expansion. That's about as big as I can go.
 
I just tried to fit a 31" tire in my about to be mini tubbed Demon and that will not fly. I am also going to have to use a 28" tire unless I want to stretch the wheel well openings. I will be running a 28x10.5x15 tire in my car. Unless you want to do a full back half that is about the most tire I would really forsee you being able to run.
 
I had a 28X13" stuff in my 69 Barracuda without mini tubbing it. It was very tight though and later switched to a 28X11 which fit much better.

My Scamp will be full with a 27X10
 
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