How low can MT DR tire pressure be set at track?

[Drewster]

Trying to launch hard on MT DRs. Blowing away at 18 psi tire press and 10psi boost. 275/60/15s
How much lower can I go?


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[turb0buick57]

Depends on how good the track prep is and suspension mods. Passenger side air bag at 20 ...driver side at 8-10..and I've been able to get away with 16.5-17 in the drag radials

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[wb_7354]

I normally run 17#. I’ve run as low as 14#. If possible have someone take a slow motion video. You don’t want to run over the tire. Does the car usually hook good? Check things over really well. How are others doing with traction on the particular day?


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[wb_7354]

Trying to launch hard on MT DRs. Blowing away at 18 psi tire press and 10psi boost. 275/60/15s
How much lower can I go?


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What tire? How old are they?


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[SpeedRacerX]

I assume you heated them well with a significant burnout?

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[Drewster]

Tires are less than a year old and I have a line lock, got them pretty hot. I’ve got HR sway bar, airbags,LCA’s Can hook good around 7 to 8 pounds boost but I would like to launch with more

 

[SpeedRacerX]

Tires are less than a year old and I have a line lock, got them pretty hot. I’ve got HR sway bar, airbags,LCA’s Can hook good around 7 to 8 pounds boost but I would like to launch with more

What did you have the bags set on? I have a similar rear suspension setup and too much air will make the car basketball bounce after the first squat. One of the best things you do in this situation is to have someone video your launch. You can learn a lot.

I had my best launch relying on the HR bar and little to no air in the bags. 1.63 60-foot leaving at about 12-15# with the e-brake method. I don't have line lock.


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[Fat Nat]

It's all in your suspension if the tire pressure in a radial is as low as your trying to run it's probably squaring the tire and blowing them off .

 

[fast86gn]

With bone stock rear suspension other than air bags and Bilstein shocks I've ran 13-14lbs of air with good results.

 

[Chuck Leeper]

Air bags... Not a good substitute for a quality adjustable shock. {At both ends of the car.}

 

[dynoman]

With that HR bar you don't need the air bags , unless you need them to keep the tires from rubbing .
Like Chuck said , shocks help a lot . Adjustable fronts can be set to let the front end rise faster for better weight transfer to plant the rears .
I usually run 15 lbs , but have gone lower to 13 lbs on a poorly prepped track .

 

[Drewster]

Good info! The bags are at 5psi to keep from rubbing


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[Jerryl]

Hey Drewster.
If you haven't yet done so, spend some time reading about Instant Center by Kevin Slaby. My eyes were opened years ago on this subject.

http://www.baselinesuspensions.com/

Take care!

 

[ETraugott]

i run 20 psi in tires. they hook great at @15 psi launch

 

[Drewster]

all good info guys. my best 60ft was 1.53 with a 7-8# launch. Always looking to do better.

 

[Mr.Spool]

my best 60ft was 1.53 with a 7-8# launch. Always looking to do better.

drop the tire pressure down to 10psi and evaluate from there,preload the airbag,25psi in the RT,10psi in the LT.generally speaking the radials will go faster with more psi provided it takes the hit,however on hard hitting combos the radial can be shocked into wheelspin needing the lower pressure to allow the sidewall to work better.it can be overcome with contact patch and power mgmt but the 275/60 is light on contact patch and has the stiffer sidewall.the pro is a much better choice due to the sidewall being softer so its less resistant to wheelspin from initial shock

 

[Drewster]

Sounds good! I’ll give it a spin
Heehee.


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[V6POWER]

I launch with 20# in my 255-60/15 MTDR @ only 8# boost and can get 1.5s.

 

[cruzn57]

my experience with low tire pressure using a drag radial , was embarrassing, as I was able to read the ads on the walls of the drag strip, I read an article from m/t stating low air pressures do not work with DR's as the tire was not designed for it, I'd work on chassis set up ,and shock set up .
when you do a burn out, look at the tire pattern on the ground, and adj tire pressure from that.

 

[Grumpy]

Like cruzn said We run high teens/really low 20s. Only come out with 3#s of boost.