Is Bigger always Better?

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Kent mosby

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Right now I have 255/60-15 mickey thompson et street ss drag radials. They are reaching the end of their life. I have Doctordiff offset shackle and have rolled wheel wells. With my shortened rear end I can fit a larger 275/60-15 tire without any rubbing. The 255s are 27.3 inch diameter, section width of 10.1 and tread width of 8.8 inches. The 275s are 28.2 dia. , 11.1 section width and 9.3 tread width. 8 inch rims

While obviously having more tread width will provide greater surface area for grip, is it better for street and drag strip. There must be a formula for determining what tire size is best for racing. What drive quality differences? I am not concerned about gas mileage.
 
Too many variables for a formula. More is better here, but the rubber compound is VERY important for traction as well. Even that varies with application - car weight, auto/stick, tire size rules, etc. Suspension has to be right to make the amount & compound of rubber on the ground to it's full potential.
 
The diameter increase also has a big effect on traction. As much or more than the width.
 
I forgot to include my current specs.
1973 Plymouth Scamp
RB 512ci, 440 source stroker kit with lightweight crankshaft, forged pistons, 10.83 CR. Trick Flow 240 heads, 440 source aluminum rockers 1.5RR, Trick flow single plane intake. Holley super sniper EFI, hyperspark ignition, coil and distributor. TTI 2 inch headers. Hughes 3000 stall converter. 727 transmission with transgo tf2 valve body mods. B&M Quicksilver shifter. Gear vendors overdrive to 8 3/4 rear end with 3.91 gears, braced in back. SS leaf springs. Competition engineering race shocks. Pypes exhaust 3" into 2.5 inch. RacePro mufflers. Mickey Thompson ET street SS Drag radials 255/60-15 27.3 inch) but possibly going to 275/60-15 28.2 inch diameter. Current cam specs 244/252 @ .050”, 282/290 adv, .516”/.537” lift(1.5:1 rocker), 112 sep, .016”/.018” lash, Solid lifter from Oregon Cams.
 
For me, it's a no-brainer. Get the bigger tires.
I would only go to smaller tires to run a "small tire" class. And 275s are still a small tire.
Edit: Just saw your specs. If you were running a 273 the extra height might have slowed you down.
512....you need all the tire you can get.
 
I am not racing in a class as the drag strip is closed this year in Spokane WA. Last year I only did test and tune. The car still needs much tuning but I hope to get into low 11s. If not, my heart will not be broken. There is always more work to get it right.
 
I’m pretty confident you’ll see low 11 second times out of that with tuning as long as you can get traction. I know someone doing low 11’s with a 512 in a B body (‘69 Charger) that doesn’t have as much motor as you got. I would put the tallest and widest tire I could fit onto it.
 
Kent mosby said:
I am not racing in a class as the drag strip is closed this year in Spokane WA. Last year I only did test and tune. The car still needs much tuning but I hope to get into low 11s. If not, my heart will not be broken. There is always more work to get it right.
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I suggest getting a set of slicks for track use, you will be dollars and ET ahead when all said and done.
Get a set of standard street radials for the street. The street eats up soft compound.
 
fishmens67 said:
I suggest getting a set of slicks for track use, you will be dollars and ET ahead when all said and done.
Get a set of standard street radials for the street. The street eats up soft compound.
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I am considering this. I have only used the MT drag radials. What street tire do you recommend?
 
Kent mosby said:
I am considering this. I have only used the MT drag radials. What street tire do you recommend?
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I RUN 295 60 D15 QUICKTIME PRO`S ,TREADED SLICKS , STICKY AND DONT WEAR REAL WELL, BUT THEY GET WITH THE PROGRAM!
Same set up , except the front of the wheel wells are contoured to the inner fender panels, which is the e
thumbnail.jpg
xact same contour as stock.
 
bob mCcarty said:
I RUN 295 60 D15 QUICKTIME PRO`S ,TREADED SLICKS , STICKY AND DONT WEAR REAL WELL, BUT THEY GET WITH THE PROGRAM!
Same set up , except the front of the wheel wells are contoured to the inner fender panels, which is the eView attachment 1715783357 xact same contour as stock.
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I like the look of those. I only have 3/4 inch on the inside and 1 1/4 and maybe some change on the outside to spare. My car sits much lower than yours. I don't think that changes the clearances. The 295s are too wide to fit as they are 1.9 inches wider than what I have. Maybe with spacers and more body work I could do it. Strange that the hoosier 275s are smaller than the 255 MT. Someone has the data messed up
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With a 512, your car should take 275 60s and act like they aren't even there. Much less what it has now. That said, since they are at the end of their life span, I'd go to the 275.
 
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