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07-21-2014, 02:22 AM | #1 |
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Going from 275radial to 30x9 ?
hi,
long time watcher from Australia with a tyre question Is there much to be gained (or lost) from going from a 275/60R15(28") Hoosier to a 30x9 Radial ? Bit less sixty foot , more MPH ? Better footprint for traction ? I have a 68 Satellite with a 440+0.055,TF727,5000 stall , 4.10 geared Strange 60 . Caltracs,Rancho rear shocks,QA1 front shocks . Average sixty is 1.52/3, best of 1.50. Car weighs 3657lbs with me in it .Ran 10.965@115 on the brakes on Saturday.Car is a daily driver street car .Car is foot braked , at least for the time being Your cars are the nearest to how I like to run mine though I run Super Street , 11.00-12.99 DYO, no Stock /Super Stock like you here plus my wallet isn't that deep Any thoughts appreciated Tex |
07-21-2014, 12:52 PM | #2 |
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Re: Going from 275radial to 30x9 ?
Is 4.10 going to be enough gear when going to a taller tire...Hoosier 18210C07?
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07-21-2014, 02:21 PM | #3 |
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Re: Going from 275radial to 30x9 ?
I would guess ET may be quicker by a few due to a harder hook and mph will decrease a few due to less wheel speed at the hit.
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07-21-2014, 05:52 PM | #4 |
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Re: Going from 275radial to 30x9 ?
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07-23-2014, 01:00 AM | #5 |
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Re: Going from 275radial to 30x9 ?
Assuming good traction, a change to a 30 inch tall tire would require roughly a 4.4 gear to turn the engine the same RPM, so if you can take a little more RPM a 4.56 gear should work nicely. & be quicker. (depending on your powerband)
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Dave Noll, E/FS ,L/SA 6526 |
07-24-2014, 05:56 PM | #6 |
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Re: Going from 275radial to 30x9 ?
thanks Dave,
funny as it seems I only shift at 6000,trap around 63/6400. not sure of pulling harder with the rods(ly with ARP bolts),peak power on chassis dyno is around 5500 but pulls happily to 6500 never went past here I did used to run 3.9 gears with the 28" as to quicker with more gear - car is able to run faster than the class Tex |
07-25-2014, 01:32 PM | #7 |
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Re: Going from 275radial to 30x9 ?
Well if your peak is 5500 & you figure 5% past peak for a trap then your current gear should be correct. But just putting a taller tire on what you have your 60' will be slower but the motor will be happier in the light's. test, test, test.
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Dave Noll, E/FS ,L/SA 6526 |
07-25-2014, 11:25 PM | #8 |
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Re: Going from 275radial to 30x9 ?
Thanks Dave,
Wiil check with hoosier for age of 30x9 slicks i have Then off to test Tex |
08-04-2014, 06:04 PM | #9 |
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Re: Going from 275radial to 30x9 ?
Dave ,
just an update . Tested on Saturday . You were right re gearing it did feel a little soft through the top end . But the 60 wasn't that much different to talk about .1.542/1.541/1.532/1.543 I was wrong in that I didn't pick up any MPH . I back to backed the 30x9 against the 275 both Hoosier radials , the 30x9 is several years ,maybe 5 or 6 , old and the 275 about 55 passes and gone after the last pass . the 30x9 went 6.920/919 @98.71/98.59MPH( 1/8")10.936/942@121.07/120.93MPH . 733/794 DA the 275 went 6.880/886@99.14/99.30MPH(1/8") 10.881/884@121.85/121.90 MPH. 387/405DA Car obviously likes a little more gear thanks again, Tex |
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