First off, thanks to the guys stepping in helping me get my car right for the track...sorry about the multiple threads.

I'm planning on buying some ET Drags (first time on a slick) for the car in the spring, and I need to determine what size tire would compliment my set up the best. I've been messing with some calculators online to see what size I need. I run 96 MPH in the 1/8th and currently have pretty poor 1.9x 60 ft with drag radials. From my calculations, my 275/40/17 BFG Drag radial has a diameter of 25.66" according to some basic algebra formulas I found on Tire Rack.


Using an online calculator at Wallace Racing's website (inputting the current 25.66" tire), my trap speed in third gear (1.43 ratio) should be 6200 RPM with my stock 3.46 rear, using my 96 MPH trap speed last time out. So, from this information it would seem going to a 27" or larger tire would be a bad idea because it will lower my trap RPM correct? My peak power is about 6250 RPM so don't I want to run a 26"?

Also, Im not able to change the rear gear at this time so Im working with what I got.

 

Also, shift light is currently set to 6500 RPM if that matters. Some have told me I need the 28" because of the combination of the M6 and me having a roots blower (tons of low end tq)

 

No opinions?

 

I am of the opinion the more tire the better . I run a 26" on my T/A , but dont make big power . The truck i run a 28 x 10.5 totally different set up . If the track gets marginal a bigger tire will help you get down it . Are you Test and tuning or bracket / index racing ? I actually thought this was a front tires thread .

 

Just T&T for now. Once I get it dialed in I'd like to start bracket racing on Saturdays

 

A little more info on the car and setup would help.

Are you running 1/8 mile only?

 

Sorry, I didn't consider that being a factor before, but now that I think about it I guess you really need to pick your tire based on either 1/8 or 1/4 huh? Ill be running primarily 1/8th with a few trips to the 1/4 a year.

More details on the car

2004 GTO 3800 LBS
M6 with stock GTO trans (2.97, 2.07, 1.43, 1.00, 0.84, 0.57 )
3.46 rear gear
LS1/ Maggie 112 HH 10 PSI (530/505)
Monster lvl III clutch
Blower cam/ TFS heads/ valve train
Strange double adjustable suspension

 

last time at the track (1/8th mile) with a 25.6" drag radial I was trapping in third gear between 6000 and 6500 at 96 MPH and a 1.95 60 ft. it was my first time so I didn't think to look at the RPM more closely.

 

I think I've decided on the 26" for my set up. I was hoping to get the Hoosier slick with C07 compound (ideal for M6 I'm told) but all the 26" tires are D06 compound, whats up with that?

 

what's your current 1/8th mile ET with the 96mph? 60 foot needs improvement also.

 

tall tire may help traction and 60ft... shorter tire typically helps top end... its a balance... but I would be more concerned with getting better 60ft.

my car's 60ft is 1.58 ---I run a M/T 275/60R15 and trap about 99-100 mph in the 1/8th
of course my car is lighter at 3050 w/o me and E/T is 6.9-7.0

 

ET was 8.01, hoping the bias plys will help a lot with the 60',since my drag radials just spun being a stick car.

 

I think part of your problem is 17's and DR's... Sticks seem to need/like softer sidewall and more is better so I understand.

 

On mine in the 1/8th I hit 8.0 - 8.1 with pump gas, I run 28/9.5x15 mickeys and I have about 1.70 1.80 60' I have 4.11s in a 12 bolt with a stalled auto. I say run the 27
but I love 28s. The 17s will kill you at the strip also man, but some people love them

 

Heavy car with a m6 I would go 28s stiff wall. The more sidewall the better. If you need to rear gear it I would to preform well with the increase tire height.