I had almost no trouble fitting 325/50-15 on 10s into the factory tubs of my LOWERED 68 Barracuda FB. Just offset spring and some accurate metal stretching. I wanted to run a pair of kidney-bean slot mags I had with a 4.5 bs; so I had to get the rear end narrowed.
295/50-15s fit with no mods whatsoever, except of course, the springs had to be moved.
For 275/60-15s I had to move the axle back a tad, which I did with fabricated spacers between the front spring perch and the spring mount. I think I got 3/8 on that deal. Whatever it was,it was the max amount on the existing factory studs, and it was enough.
If you drive like I do around corners on city streets, you will need 295s, for sideways-sliding rubber, and power-sliding. Anything less and you will be doing 180*s in traffic. The thing is, while sliding, the brakes make it worse and as soon as the wheels stop turning, you are in an uncontrollable slide, usually a spin..
But if you are more of a point and shoot kind of guy, then none of those sizes, in BFG/Coopers are worth a fart. So you might as well go with the tallest; I think they have a slightly better traction patch, plus you can run more pressure in the tall boys. My 295s on 10s run at 24psi to keep the tread flat to the road.
>Because of the traction issues on the street, it doesn't much matter what rear-end you run (short of a 7.25) nor what gears you run, cuz the tires will be spinning to past most speed limits anyways.
>If you have more than about a 12/1 starter gear with a lo-stall TC, first gear becomes too low to be useful.
On the street, more stall does the same thing... because it's not actually the gears that are the problem, really it is the amount of torque getting to the road that is the issue.
>In my experience 295 BFG/Cobras take about 2000 calculated foot pounds to break traction, and they need about 2500 to powerslide with any degree of control.
>So if you had a 318, that put down just 130 ftlbs at 2000 rpm stall; then it would need a starter gear of 15.38, which, with a 2.45 low gear means 6.30s. But that is with zero TM (TorqueMultiplication) inside the TC, which never happens. Most TCs are gonna have, at ZERO mph, a hydraulic TM of about 1.8, so,6.30/1.8- 3.55s will break the tires loose. However, 3.55s may not sustain the spin for very far. But worse is that the TC will start dropping TM immediately as the car gains speed, and it will lose TM at a faster rate than the poor 318 can build with rpm.
>But with a stroker, and say a 2800TC, your engine output could be what?, pushing 350ftlbs? (just guessing). Lets just say yes, then to break traction, you would need 2000/350= a starter gear of just 5.71. And if your TC also has a 1.8 multiplier then 5.81/1.8=3.17, and with a 2.45 low gear, this is further reduced to 1.30 rear gear. See what I mean...
But to sustain a good second gear powerslide, you might need 3000 ftlbs so; 3000/350=857, and divide by 2.45=3.50 rear gear at 1.0 in the TC which never happens, lol. At 35 mph, your TC might be down to 1.3 so 3.50/1.3=2.69 rear gear.
Like I said, I ran every gear you can imagine with my Hi-Torque 367.
The point is, just run what you got for a while and see how you like it. Stroker-torque is baddazz.
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I only have a 367, but I ran it with almost every gear you can imagine from 2.76 to 4.30s, and a few beyond that too. But I have a clutch. 3.23s were my favorite, until I got a GVod. Then I ran 4.30s for a while. Eventually I got a lower first gear for the trans, and then went to 3.55s.
My second gear is 3.55x1.92 x no TC, so 6.816 . This engine, in second gear, will initiate a spin anywhere below 50 mph . At 35mph she is spinning ~3000. It's a stomp-it and slide deal, backing off as may be required to rear-steer the car.
For that to be possible my engine must be putting down;
3000/6.816=440 ftlbs at 3000 rpm. Or more likely, the 295s don't take 3000ftlbs to break traction at 35 mph.
So lets do yours again at 350 ftlbs to sustain a slide with a 2800ftlb requirement. I get 3.91s now.But if you had 388 ftlbs then 3.55s. The point here is that for every 1% more torque your engine makes, you can drop the same amount of rear gear.
I think the point is to run what you got and let it tell you if or where it is lacking. This way you get it right on the first try.
As for the TC, you kindof want the stall to be such that it is more or less locked up at your cruising speed, strictly to reduce the heat of slippage.
So; with 275/60-15s (88" roll-out), for ZERO-slip;I get
With 3.55s, 65=2770, 85=3620
With 3.23s, 65=2520, 85=3300
With 2.94s, 65=2290, 85=3000
With 2.94s, 65=2420, 85=3160, with 295/50-15s
Pick your poison.
