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

Re: Going from 275radial to 30x9 ?
 

Is 4.10 going to be enough gear when going to a taller tire...Hoosier 18210C07?

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.

Re: Going from 275radial to 30x9 ?
 

thanks for the replies ,
I was looking at either the 18209C06 or 18210C07 tyre
I may not quite get 18211 or 18212 into the stock wheel well
thanks,

http://i1018.photobucket.com/albums/...032012DOTD.jpg

Tex

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)

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

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. :)

Re: Going from 275radial to 30x9 ?
 

Thanks Dave,
Wiil check with hoosier for age of 30x9 slicks i have
Then off to test

Tex

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