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Thread: What size slicks?

  1. #1
    Member JUNIOR BUILDER
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    Apr 2007
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    What size slicks?

    Looking for a little advice on what slicks I should start with.

    '66 Chevy II
    Four link and tubbed
    Blown 355 SBC
    500 ft/lbs @ 3000 RPM
    630 HP @ 6100 RPM
    TH400 with Trans brake
    4:11 in Ford 9"

    I have an extra pair of 15x15 wheels.

    Hope to get it on the track this Spring.

    Thanks in advance

    Steve

  2. #2
    Member JUNIOR BUILDER
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    Maybe it will help if I narrow it down.

    Should I go with the widest slicks I can fit under the car? Is there a point with a SBC that I am just adding unsprung weight?

  3. #3
    Senior Member DYNO OPERATOR
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    Apr 2008
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    The final RPM that you are willing to turn at the finish line will be the deciding factor on the diameter. The 4.11 gear is going to need a short tire to give your mouse much leverage off the start line. a 100" roll out tire. For instance if you think you are capable of say 137 MPH in the Q. with your 4.11 gear and an auto trans with a good converter and a 100 roll out tire your RPM in the traps should be near 6240. If that sounds low RPM for your motor then you might look at a shorter roll tire. I use this rule for guessing RPM differences, for every inch change in tire roll out the final rpm will change about 75 RPM +or- a few. If you think that your hot rod is going to eclipse 137 MPH say, 145 then your RPM with the 100" tire might be 6600RPM in the traps. I am sure that you are seeing a trend here on the tire question now. The tire roll out is the paramount variable, this issue usually leaves you with a narrowing tire choice for widths and compounds. I run a 3 speed trans in my 7 second door car and of course the more tire patch you can get under the car the more forgiving the traction. When you end up with a little tire in roll out the only way to recapture the foot print is by width. If your car is not restrictive in the wheel tub area and you are a bracket racer. Most folks go for the width so you don't have to have a perfect start line every time to get out of the box. Don't run tubes in your slicks to keep the mass down and to be safe. Get what is available for roll out and get the wide one would be the best advice one could give you until you know exactly how fast your car will run the Q. your tire roll out the second purchase will be more clear once you run something of a known roll and get a result. Borrow a buddy's to see what your car likes then you will have more info to get that expieremental purchase behind you. Your 4.11 gear may be the next issue you might look at if you had say 4.56 you could look at larger diameter tires or be able to RPM with out buying shorter tires yet if the RPM's I stated are low for you.
    Sorry about the bad spelling.
    You make your own luck, the better the info you are working with the better your luck. Have fun and Good luck

  4. #4
    Senior Member RACING JUNKIE
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    Id run the biggest tire you have. I think your SBC will pull the 4.11 since your running a turbo 400. That low first gear in your trans will make up the difference. A SBC with a blower will leave harder than a moderate BBC without a blower. 500ft of torque is nothing to laugh at even if it is a mouse motor. JMO

  5. #5
    Member JUNIOR BUILDER
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    Will a 32 x 14.5-15 slick work on a 15 x 15 wheel?

  6. #6
    Senior Member DYNO OPERATOR
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    Quote Originally Posted by ssym
    Will a 32 x 14.5-15 slick work on a 15 x 15 wheel?
    Yes, it will rather well.

  7. #7
    Senior Member RACING JUNKIE
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    Any particular brand recomendations?
    I've used just about every tire brand out there, hoosier, M/T goodyear, phoenix.
    I've had good and bad luck out of most but the Phoenix FX tire seems to last longer, hook harder and be more consistent (run-out)
    your thoughts here TopspeedLowet?
    Thx, Cp
    ***IN GOD WE TRUST***

  8. #8
    Senior Member MASTER BUILDER
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    I found that a Hoosier 28" Pro Dot race tire with supposedly the same specs as a Mickey Thompson, was actually 1 lb per tire lighter, and 1inch of tread wider, so I switched to Hoosier.
    It Ain't Over Til Its NOVA - 634ci of S*#t Your Pants!

  9. #9
    Senior Member DYNO OPERATOR
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    Quote Originally Posted by cepx111
    Any particular brand recomendations?
    I've used just about every tire brand out there, hoosier, M/T goodyear, phoenix.
    I've had good and bad luck out of most but the Phoenix FX tire seems to last longer, hook harder and be more consistent (run-out)
    your thoughts here TopspeedLowet?
    Thx, Cp
    I have used them all with various levels of performance and had good results with all different performance usages. For instance, If I had a tire sponsor and wanted the ultimate performance tire for a 8 second or quicker door car I would choose the good year tire with a stiff side wall and D1 compound and have the best tire available, but a tire that has the shortest useful life span. I expect in a 8.0 car to run near 55 excellent passes, or a few more baring no abuse to them like shake or J Force burn outs. The Phoenix FX tires you like are excellent firestone molds and are very fast and light. They seem to work excellent in slow to 10.0 sec car that is between light and 3400# or so. I think they are great but do not offer larger tires. They cater primarly to stocker's and mini tub cars, and fill that market real well. I noticed that they last for ever as well when I ran them. I feel that Good years are the best general tire manufacturer, and you can find a tire compound and diameter / width that will fit your car correctly, but they are expensive and may not perform as long and Mickey thompsons or Phoenix can. The Phoenix tires are a nitch that good year does not have a full line assortment of and make Phoenix in the 9.99 and slower cars my second favorite to good years. As far as roll out matching that is your suppliers issue or how they are mounted more likely. When they are mounted and air pressure is at say 20# to screw the rims the tires are getting stretched out. This is why I make sure that I have both tires from the moment I mount them at the same pressure for the same time period while I screw the rims to the tires and not a moment longer than necessary to do the job. This is how you match tire roll out by stretching the smaller tire with tire pressure for so many min to break the chords in the tire. Guys do this un knowing that they are screwing up a perfect matched set of tires by leaving the mounting pressure in the tires to long or unequal.
    Sorry that I did not see that you asked my 2 cents. here's a buck
    I hope this helps out


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