Too much tire?
#1051878
08/13/11 09:05 AM
08/13/11 09:05 AM
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Frostbitefalls MN (Rocky&Bullw...
gregsdart
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Frostbitefalls MN (Rocky&Bullw...
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I guess I already new the answer, just didn't realize it? My car went fastest with a 15.1 x 33.6 x 15 stiff sidewall tire, but is still slower than 440JIMs car. My best is a 1.259, his best is somewhere in the 1.22s. I run 8.80s Jims car is in the mid/low nines.
I kept thinking that maybe it was some roll out, better converter, what ever. But then while playing with the Dragstrip 2000 program, it showed 60 ft gains the smaller I went with the rear tires. Not small gains, but a full .02x going down to a 31.25 x 12.5 x 15. Go figure. OK chassis experts, your experiences?
P.S. I am sort of looking for that majic combo, consistancy plus speed!
Last edited by gregsdart; 08/13/11 09:07 AM.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: Too much tire?
[Re: tboomer]
#1051880
08/13/11 09:49 AM
08/13/11 09:49 AM
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Frostbitefalls MN (Rocky&Bullw...
gregsdart
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Thanks, Ted. I run a 4.56 gear, torqueflite, 6500 stall. I have some latitude on trap rpm, so a drop from a 106 roll out to 101 to 102 would be workable, as long as the tires have some growth to them. I do run a trans brake, so I assume I need at least a medium stiff sidewall tire. Goodyears smallest listed Supergas type tire comes in at 5 lbs lighter per tire, 102 roll out 14 inch tread. 
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: Too much tire?
[Re: tboomer]
#1051882
08/13/11 10:06 AM
08/13/11 10:06 AM
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Joined: May 2003
Posts: 6,558
Downtown Roebuck Ont
Twostick
Still wishing...
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Still wishing...
Joined: May 2003
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Downtown Roebuck Ont
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Shorter+lighter tire should = less rolling resistance which should = quicker. How much quicker?  but the physics should be on your side. Didn't Fred end up going faster with a smaller tire? I've forgot the details but I thought he was going to run in some tire limited class and he was surprised to still hook and go quicker. Kevin
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Re: Too much tire?
[Re: gregsdart]
#1051885
08/13/11 02:28 PM
08/13/11 02:28 PM
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Joined: Jun 2003
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Romeo MI
MR_P_BODY
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Romeo MI
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Quote:
I guess I already new the answer, just didn't realize it? My car went fastest with a 15.1 x 33.6 x 15 stiff sidewall tire, but is still slower than 440JIMs car. My best is a 1.259, his best is somewhere in the 1.22s. I run 8.80s Jims car is in the mid/low nines.
I kept thinking that maybe it was some roll out, better converter, what ever. But then while playing with the Dragstrip 2000 program, it showed 60 ft gains the smaller I went with the rear tires. Not small gains, but a full .02x going down to a 31.25 x 12.5 x 15. Go figure. OK chassis experts, your experiences?
P.S. I am sort of looking for that majic combo, consistancy plus speed!
Your talking 60' times.... JMO but your tire width
doesnt come into play(assuming traction isnt a problem)
in the 60', yes the diameter does because it changes
the rpm... I know you like to have a HIGH stall which
to me is past the power point of your engine and I
think thats where you loose your 60' but you cover
it up on top end with the revs.... down track the
tire width becomes a player with drag and wind resistance...
again JMO
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Re: Too much tire?
[Re: MR_P_BODY]
#1051886
08/13/11 05:56 PM
08/13/11 05:56 PM
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Frostbitefalls MN (Rocky&Bullw...
gregsdart
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I guess stall could affect it some. But the car did go faster overall going from 5500 to 6500. When I ran the 8.77 with a 1.27 60 ft I was running radial M/T drag slicks, 14x33 at 34 lbs each. The tires I have now are 39.2 each. Best I have been able to post with the big tires is 1.259 with an 8.86 ET.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: Too much tire?
[Re: jim sciortino]
#1051888
08/13/11 11:19 PM
08/13/11 11:19 PM
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Frostbitefalls MN (Rocky&Bullw...
gregsdart
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They were down right evil in the handling department. They would put the car into what has become known as "radial rock" or swinging side to side during the run, building as you go sometimes. It was so bad I lifted half the runs on those tires, and a couple of guys asked why I didn't lift on a couple of others. When someone can see it from the starting line, its really bad!
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: Too much tire?
[Re: gregsdart]
#1051890
08/14/11 10:38 AM
08/14/11 10:38 AM
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Joined: Jan 2003
Posts: 16,923
NC
440Jim
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I Live Here
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Greg,
Although my best times are as shown in my sig (sea level, 55 Deg), in the normal summer temps (85F) and mid life tires (100 passes), 1.275 is more typical.
Phoenix 12.2 x 31.25 W, 31.8" tall, published weight 33 lbs, plus inner tube ~9 lbs
The sig was 4.30 gears, this year 4.10, but I don't see any significant difference (just like when I put 4.56 in it when the 4.30 broke). In the beginning of this year, with 4.10 gears and 193 passes on the old slicks it did 1.241 at 57 Deg air temp (30.02"Hg good air) with a 9.18 ET.
And 26" front tires for rollout comparison.
I have thought about trying a M/T 10.5W tire, but I doubt I would get the 200+ passes on a set at 3250 lbs like I do now with the larger tire. So cost would go way up, even if it works.
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Re: Too much tire?
[Re: gregsdart]
#1051891
08/14/11 12:16 PM
08/14/11 12:16 PM
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Joined: Apr 2007
Posts: 2,026
Trumbull,CT.
jim sciortino
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Trumbull,CT.
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Quote:
They were down right evil in the handling department. They would put the car into what has become known as "radial rock" or swinging side to side during the run, building as you go sometimes. It was so bad I lifted half the runs on those tires, and a couple of guys asked why I didn't lift on a couple of others. When someone can see it from the starting line, its really bad!
Wow....that ain't good.
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Re: Too much tire?
[Re: gregsdart]
#1051892
08/19/11 09:27 PM
08/19/11 09:27 PM
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Joined: Jan 2003
Posts: 16,923
NC
440Jim
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I Live Here
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So, Greg
What decision or plan have you decided?
The 14x32 slick is a great all around tire, IMO.
Since I run the "W" version, it is wider/heavier than the non-W and works great on a 14" wide rim. Phoenix 12.2 x 31.25 W, 13.6" wide tread, 31.8" tall, published weight 33 lbs, plus inner tube ~9 lbs.
And even at 11 psi, my 3250 lb car puts a good wrinkle in that tire on launch.
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What do you have for gears and tranny? Wouldn't that come into play? 
for you,Greg! 
