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MT drag radial

Posted: Wed Jul 05, 2017 5:29 am
by steve cowan
hi guys,
i am running the older Mickey thomson drag radial on my 3500 pound streeter
my question is what is the lowest pressure i can run at the track
car runs low 11 @ 121 plus
tyre size 255/60/15
leaf spring rear with caltrcs
yes i am having traction problems,i have been told 22psi is the lowest i should run in my weight vehicle
i am prepared to bead screw the tyres to the rim and fit tubes but i dont know if this is a good idea
i have run a 265/50/15 but they rub the guards and not tall enough
any advice appriciated
steve c

Re: MT drag radial

Posted: Wed Jul 05, 2017 1:40 pm
by lefty o
i know people that run much lower pressures than 22 to get best results. also have learned that for the same size mt dr as a slick you need a wider wheel for them also.

Re: MT drag radial

Posted: Wed Jul 05, 2017 4:09 pm
by BOOT
M/T says on their site a min I think. Their older drag radials last a lot longer than the new SS

Re: MT drag radial

Posted: Wed Jul 05, 2017 8:35 pm
by fastblackracing
I run the 275 pro at 18 psi. 3650 race weight with a 9.90@136 mph with 1.37 60 foot times...

As stated, a wider than normal rim helps these tires develop a wider footprint....
and in general lower pressures do not help like they do on a bias ply slick....

These tires work best when the suspension and launch horsepower are tuned to provide a DEAD hook off the line then bring the power in fast, where as slicks will tolerate some extra wheel speed at the hit.

If your track has poor prep and the tires are older/harder and you have enough torque at the hit to spin the tires you will likely not be able to get them to work for without some re work.

To cure slippage on the rims, break the beads down and clean the tire bead and rim bead surface with alcohol and then use 3M weatherstrip adhesive on the bead surface for glue and re-inflate the tires. It works really well and you do not have to drill the rims and beads.

Re: MT drag radial

Posted: Thu Jul 06, 2017 5:39 am
by ccjohn2
According to the MT rep 16 to 18psi for that size tire. The 315's use 14 to 18psi. They also said there's no performance gain running any of them above 24psi.

Re: MT drag radial

Posted: Fri Jul 07, 2017 12:16 am
by steve cowan
Thanks guys,
There is some great information there,much appreciated
I am changing out my converter this weekend from a 9 inch 4000 rpm to a 8 inch 5600 rpm converter
I am going to bust tyres off the rim and glue as advised,I will test tyre pressures
Starting at 22 psi and work my way down to 16 as a minimum
Unfortunate the track prep is always average unless someone is doing private testing previous to our test and tune days and street series days,as time progresses I can start taking a little power out at the start if need be with programmable 6 MSD
Thanks again guys,
Steve c

Re: MT drag radial

Posted: Tue Jul 11, 2017 4:10 pm
by AMXstocker1
we run 28x10.5 probracket radial on a 3200lb car calvert leafs, bars, and shocks, the car has been 6.80 in the 1/8th at 101 with a 1.48 sixty, but it is definitely not a hook anywhere setup, especially since we've found some power its blown the tires off twice at 20 psi and the shocks are 3 clicks from dead loose, where going out this weekend and i'm going to try dead loose and 18-19 psi see if i can get a more consistent hook. oh and thats transbrake leaves off a 3600 rpm chip and flashes to right at 6000

Re: MT drag radial

Posted: Wed Jul 12, 2017 5:06 am
by steve cowan
amx,
sounds like fun ride'
can you give me any advice on shocks to use,i have koni 90/10 in the front
in the rear are only stock gas shock,
there is not alot available here in australia-koni adjustable are about all there is
the car leaves straight and does not really squat or lift in the rear on takeoff
the front of the car sits 2 inches higher than the rear
obviously it is not doing alot with a best 60ft of 1.682
the engine probably makes around 500hp but i think with alot of suspension tuning over time the car should be able to run 10.90s
it is a footbrake car and i think with the new converter i am putting in now has to be worth a coupe of tenths if i can get it to hook
any advice appriciated
steve c

Re: MT drag radial

Posted: Mon Jul 17, 2017 4:56 pm
by AMXstocker1
The right converter should be worth a couple tenths, the best advise i can give is little to no burnout just enough to get the water off if your smoking them you've done too much, and your going to have to adjust tire pressure with track conditions we blew the tires off first pass this last weekend on a 150 degree track with 19 lbs in them went down to 17 and it hooked it was the difference in a 1.80 60ft and a 1.500 60ft, i would run your front end as loose as possible 90/10's should be fine the rear we just have the calvert single adjustables that were set on a 1 the loosest setting this weekend becuase the track was terrible

Re: MT drag radial

Posted: Tue Jul 18, 2017 1:50 am
by steve cowan
Thanks amx for the advice,
I have heard the small burnout deal with the radial,
Most guys punish there tyres in the water box
I have been told before, tyres should be near same temperature as the track to have a better chance of working
I am testing this weekend and its winter here
Night temperature down to 5 degrees Celsius so the track goes cold, plus powder from street tyres on the track won't help either

Re: MT drag radial

Posted: Sun Jul 23, 2017 1:35 am
by steve cowan
amx,
i went test and tune last night,it was very busy so i only managed 2 x runs
last meeting the car ran 11.42 with a 1.78 sixty ft tyres on 24 psi

last night
1st run 11.31 @ 120.94
1.72 sixty ft small burnout and 22psi in rear tyres wheel spun on startline
2nd run 11.100 @ 120.65
1.57 sixty with a bigger burnout and dead hooked of the line
at 19psi in the rear tyres
remember i am using the older M/T street radial
the pro radial is not legal here but can use the older style M/T
NEW 5600 EIGHT INCH CONVERTER FITTED THIS WEEK
i was only bringing up to 2500 rpm on the footbrake

Re: MT drag radial

Posted: Sun Jul 23, 2017 7:21 am
by tenxal
steve cowan wrote:...i am prepared to bead screw the tyres to the rim and fit tubes but i dont know if this is a good idea....
Never use rims screws with radials.

Re: MT drag radial

Posted: Mon Jul 24, 2017 4:41 am
by steve cowan
Texnel,
Would you mind explaining why if you don't mind, I am curious
Thanks Steve C

Re: MT drag radial

Posted: Mon Jul 24, 2017 8:56 am
by tenxal
M/T (and Hoosier) don't recommend it, as the bead area of the tire can be severely damaged. I've seen one set ruined by doing it...not pretty. Make a call to M/T for their recommendation.

Re: MT drag radial

Posted: Mon Jul 24, 2017 6:02 pm
by steve cowan
Texnel,
Appreciate your response
At the end of the day is if I want to run the 255 radial deal it is about managing start line power the same as everyone else
I want to persevere with the 255
I am experimenting with tyre pressures
I really did not want to drill my brand new black anodised weld racing rims anyhow lol
Steve c